diff --git a/fastNLP/core/action.py b/fastNLP/core/action.py
index ef595cbb..d36d350d 100644
--- a/fastNLP/core/action.py
+++ b/fastNLP/core/action.py
@@ -168,19 +168,7 @@ class BaseSampler(object):
 
     """
 
-    def __init__(self, data_set):
-        """
-
-        :param data_set: multi-level list, of shape [num_example, *]
-
-        """
-        self.data_set_length = len(data_set)
-        self.data = data_set
-
-    def __len__(self):
-        return self.data_set_length
-
-    def __iter__(self):
+    def __call__(self, *args, **kwargs):
         raise NotImplementedError
 
 
@@ -189,16 +177,8 @@ class SequentialSampler(BaseSampler):
 
     """
 
-    def __init__(self, data_set):
-        """
-
-        :param data_set: multi-level list
-
-        """
-        super(SequentialSampler, self).__init__(data_set)
-
-    def __iter__(self):
-        return iter(self.data)
+    def __call__(self, data_set):
+        return list(range(len(data_set)))
 
 
 class RandomSampler(BaseSampler):
@@ -206,17 +186,9 @@ class RandomSampler(BaseSampler):
 
     """
 
-    def __init__(self, data_set):
-        """
+    def __call__(self, data_set):
+        return list(np.random.permutation(len(data_set)))
 
-        :param data_set: multi-level list
-
-        """
-        super(RandomSampler, self).__init__(data_set)
-        self.order = np.random.permutation(self.data_set_length)
-
-    def __iter__(self):
-        return iter((self.data[idx] for idx in self.order))
 
 
 class Batchifier(object):
diff --git a/fastNLP/core/batch.py b/fastNLP/core/batch.py
new file mode 100644
index 00000000..0a5e9712
--- /dev/null
+++ b/fastNLP/core/batch.py
@@ -0,0 +1,126 @@
+from collections import defaultdict
+
+import torch
+
+from fastNLP.core.dataset import DataSet
+from fastNLP.core.field import TextField, LabelField
+from fastNLP.core.instance import Instance
+
+
+class Batch(object):
+    """Batch is an iterable object which iterates over mini-batches.
+
+    ::
+        for batch_x, batch_y in Batch(data_set):
+
+    """
+
+    def __init__(self, dataset, batch_size, sampler, use_cuda):
+        self.dataset = dataset
+        self.batch_size = batch_size
+        self.sampler = sampler
+        self.use_cuda = use_cuda
+        self.idx_list = None
+        self.curidx = 0
+
+    def __iter__(self):
+        self.idx_list = self.sampler(self.dataset)
+        self.curidx = 0
+        self.lengths = self.dataset.get_length()
+        return self
+
+    def __next__(self):
+        """
+
+        :return batch_x: dict of (str: torch.LongTensor), which means (field name: tensor of shape [batch_size, padding_length])
+                         batch_x also contains an item (str: list of int) about origin lengths,
+                         which means ("field_name_origin_len": origin lengths).
+                         E.g.
+                         ::
+                         {'text': tensor([[ 0,  1,  2,  3,  0,  0,  0], 4,  5,  2,  6,  7,  8,  9]]), 'text_origin_len': [4, 7]})
+
+                batch_y: dict of (str: torch.LongTensor), which means (field name: tensor of shape [batch_size, padding_length])
+                All tensors in both batch_x and batch_y will be cuda tensors if use_cuda is True.
+                The names of fields are defined in preprocessor's convert_to_dataset method.
+
+        """
+        if self.curidx >= len(self.idx_list):
+            raise StopIteration
+        else:
+            endidx = min(self.curidx + self.batch_size, len(self.idx_list))
+            padding_length = {field_name: max(field_length[self.curidx: endidx])
+                              for field_name, field_length in self.lengths.items()}
+            origin_lengths = {field_name: field_length[self.curidx: endidx]
+                              for field_name, field_length in self.lengths.items()}
+
+            batch_x, batch_y = defaultdict(list), defaultdict(list)
+            for idx in range(self.curidx, endidx):
+                x, y = self.dataset.to_tensor(idx, padding_length)
+                for name, tensor in x.items():
+                    batch_x[name].append(tensor)
+                for name, tensor in y.items():
+                    batch_y[name].append(tensor)
+
+            batch_origin_length = {}
+            # combine instances into a batch
+            for batch in (batch_x, batch_y):
+                for name, tensor_list in batch.items():
+                    if self.use_cuda:
+                        batch[name] = torch.stack(tensor_list, dim=0).cuda()
+                    else:
+                        batch[name] = torch.stack(tensor_list, dim=0)
+
+            # add origin lengths in batch_x
+            for name, tensor in batch_x.items():
+                if self.use_cuda:
+                    batch_origin_length[name + "_origin_len"] = torch.LongTensor(origin_lengths[name]).cuda()
+                else:
+                    batch_origin_length[name + "_origin_len"] = torch.LongTensor(origin_lengths[name])
+            batch_x.update(batch_origin_length)
+
+            self.curidx += endidx
+            return batch_x, batch_y
+
+
+if __name__ == "__main__":
+    """simple running example
+    """
+    texts = ["i am a cat",
+             "this is a test of new batch",
+             "haha"
+             ]
+    labels = [0, 1, 0]
+
+    # prepare vocabulary
+    vocab = {}
+    for text in texts:
+        for tokens in text.split():
+            if tokens not in vocab:
+                vocab[tokens] = len(vocab)
+    print("vocabulary: ", vocab)
+
+    # prepare input dataset    
+    data = DataSet()
+    for text, label in zip(texts, labels):
+        x = TextField(text.split(), False)
+        y = LabelField(label, is_target=True)
+        ins = Instance(text=x, label=y)
+        data.append(ins)
+
+    # use vocabulary to index data
+    data.index_field("text", vocab)
+
+
+    # define naive sampler for batch class
+    class SeqSampler:
+        def __call__(self, dataset):
+            return list(range(len(dataset)))
+
+
+    # use batch to iterate dataset
+    data_iterator = Batch(data, 2, SeqSampler(), False)
+    for epoch in range(1):
+        for batch_x, batch_y in data_iterator:
+            print(batch_x)
+            print(batch_y)
+            # do stuff
diff --git a/fastNLP/data/dataset.py b/fastNLP/core/dataset.py
similarity index 55%
rename from fastNLP/data/dataset.py
rename to fastNLP/core/dataset.py
index ffe75494..5f749795 100644
--- a/fastNLP/data/dataset.py
+++ b/fastNLP/core/dataset.py
@@ -7,23 +7,36 @@ class DataSet(list):
         self.name = name
         if instances is not None:
             self.extend(instances)
-    
+
     def index_all(self, vocab):
         for ins in self:
             ins.index_all(vocab)
-    
+
     def index_field(self, field_name, vocab):
         for ins in self:
             ins.index_field(field_name, vocab)
 
     def to_tensor(self, idx: int, padding_length: dict):
+        """Convert an instance in a dataset to tensor.
+
+        :param idx: int, the index of the instance in the dataset.
+        :param padding_length: int
+        :return tensor_x: dict of (str: torch.LongTensor), which means (field name: tensor of shape [padding_length, ])
+                tensor_y: dict of (str: torch.LongTensor), which means (field name: tensor of shape [padding_length, ])
+
+        """
         ins = self[idx]
         return ins.to_tensor(padding_length)
-    
+
     def get_length(self):
+        """Fetch lengths of all fields in all instances in a dataset.
+
+        :return lengths: dict of (str: list). The str is the field name.
+                The list contains lengths of this field in all instances.
+
+        """
         lengths = defaultdict(list)
         for ins in self:
             for field_name, field_length in ins.get_length().items():
                 lengths[field_name].append(field_length)
         return lengths
-
diff --git a/fastNLP/data/field.py b/fastNLP/core/field.py
similarity index 65%
rename from fastNLP/data/field.py
rename to fastNLP/core/field.py
index ada90857..eb2bc78e 100644
--- a/fastNLP/data/field.py
+++ b/fastNLP/core/field.py
@@ -1,18 +1,23 @@
 import torch
 
+
 class Field(object):
+    """A field defines a data type.
+
+    """
+
     def __init__(self, is_target: bool):
         self.is_target = is_target
 
     def index(self, vocab):
-        pass
-    
+        raise NotImplementedError
+
     def get_length(self):
-        pass
+        raise NotImplementedError
 
     def to_tensor(self, padding_length):
-        pass
-        
+        raise NotImplementedError
+
 
 class TextField(Field):
     def __init__(self, text: list, is_target):
@@ -31,25 +36,38 @@ class TextField(Field):
         return self._index
 
     def get_length(self):
+        """Fetch the length of the text field.
+
+        :return length: int, the length of the text.
+
+        """
         return len(self.text)
 
     def to_tensor(self, padding_length: int):
+        """Convert text field to tensor.
+
+        :param padding_length: int
+        :return tensor: torch.LongTensor, of shape [padding_length, ]
+        """
         pads = []
         if self._index is None:
-            print('error')
+            raise RuntimeError("Indexing not done before to_tensor in TextField.")
         if padding_length > self.get_length():
-            pads = [0 for i in range(padding_length - self.get_length())]
-        # (length, )
+            pads = [0] * (padding_length - self.get_length())
         return torch.LongTensor(self._index + pads)
-        
+
 
 class LabelField(Field):
     def __init__(self, label, is_target=True):
         super(LabelField, self).__init__(is_target)
         self.label = label
         self._index = None
-    
+
     def get_length(self):
+        """Fetch the length of the label field.
+
+        :return length: int, the length of the label, always 1.
+        """
         return 1
 
     def index(self, vocab):
@@ -58,13 +76,13 @@ class LabelField(Field):
         else:
             pass
         return self._index
-    
+
     def to_tensor(self, padding_length):
         if self._index is None:
             return torch.LongTensor([self.label])
         else:
             return torch.LongTensor([self._index])
 
+
 if __name__ == "__main__":
-    tf = TextField("test the code".split())
-    
+    tf = TextField("test the code".split(), is_target=False)
diff --git a/fastNLP/core/instance.py b/fastNLP/core/instance.py
new file mode 100644
index 00000000..3322e576
--- /dev/null
+++ b/fastNLP/core/instance.py
@@ -0,0 +1,53 @@
+class Instance(object):
+    """An instance which consists of Fields is an example in the DataSet.
+
+    """
+
+    def __init__(self, **fields):
+        self.fields = fields
+        self.has_index = False
+        self.indexes = {}
+
+    def add_field(self, field_name, field):
+        self.fields[field_name] = field
+
+    def get_length(self):
+        """Fetch the length of all fields in the instance.
+
+        :return length: dict of (str: int), which means (field name: field length).
+
+        """
+        length = {name: field.get_length() for name, field in self.fields.items()}
+        return length
+
+    def index_field(self, field_name, vocab):
+        """use `vocab` to index certain field
+        """
+        self.indexes[field_name] = self.fields[field_name].index(vocab)
+
+    def index_all(self, vocab):
+        """use `vocab` to index all fields
+        """
+        if self.has_index:
+            print("error")
+            return self.indexes
+        indexes = {name: field.index(vocab) for name, field in self.fields.items()}
+        self.indexes = indexes
+        return indexes
+
+    def to_tensor(self, padding_length: dict):
+        """Convert instance to tensor.
+
+        :param padding_length: dict of (str: int), which means (field name: padding_length of this field)
+        :return tensor_x: dict of (str: torch.LongTensor), which means (field name: tensor of shape [padding_length, ])
+                tensor_y: dict of (str: torch.LongTensor), which means (field name: tensor of shape [padding_length, ])
+
+        """
+        tensor_x = {}
+        tensor_y = {}
+        for name, field in self.fields.items():
+            if field.is_target:
+                tensor_y[name] = field.to_tensor(padding_length[name])
+            else:
+                tensor_x[name] = field.to_tensor(padding_length[name])
+        return tensor_x, tensor_y
diff --git a/fastNLP/core/preprocess.py b/fastNLP/core/preprocess.py
index f8142c36..b7c33f3b 100644
--- a/fastNLP/core/preprocess.py
+++ b/fastNLP/core/preprocess.py
@@ -3,6 +3,10 @@ import os
 
 import numpy as np
 
+from fastNLP.core.dataset import DataSet
+from fastNLP.core.field import TextField, LabelField
+from fastNLP.core.instance import Instance
+
 DEFAULT_PADDING_LABEL = '<pad>'  # dict index = 0
 DEFAULT_UNKNOWN_LABEL = '<unk>'  # dict index = 1
 DEFAULT_RESERVED_LABEL = ['<reserved-2>',
@@ -84,7 +88,7 @@ class BasePreprocess(object):
         return len(self.label2index)
 
     def run(self, train_dev_data, test_data=None, pickle_path="./", train_dev_split=0, cross_val=False, n_fold=10):
-        """Main preprocessing pipeline.
+        """Main pre-processing pipeline.
 
         :param train_dev_data: three-level list, with either single label or multiple labels in a sample.
         :param test_data: three-level list, with either single label or multiple labels in a sample. (optional)
@@ -92,7 +96,9 @@ class BasePreprocess(object):
         :param train_dev_split: float, between [0, 1]. The ratio of training data used as validation set.
         :param cross_val: bool, whether to do cross validation.
         :param n_fold: int, the number of folds of cross validation. Only useful when cross_val is True.
-        :return results: a tuple of datasets after preprocessing.
+        :return results: multiple datasets after pre-processing. If test_data is provided, return one more dataset.
+                If train_dev_split > 0, return one more dataset - the dev set. If cross_val is True, each dataset
+                is a list of DataSet objects; Otherwise, each dataset is a DataSet object.
         """
 
         if pickle_exist(pickle_path, "word2id.pkl") and pickle_exist(pickle_path, "class2id.pkl"):
@@ -111,68 +117,87 @@ class BasePreprocess(object):
             index2label = self.build_reverse_dict(self.label2index)
             save_pickle(index2label, pickle_path, "id2class.pkl")
 
-        data_train = []
-        data_dev = []
+        train_set = []
+        dev_set = []
         if not cross_val:
             if not pickle_exist(pickle_path, "data_train.pkl"):
-                data_train.extend(self.to_index(train_dev_data))
                 if train_dev_split > 0 and not pickle_exist(pickle_path, "data_dev.pkl"):
-                    split = int(len(data_train) * train_dev_split)
-                    data_dev = data_train[: split]
-                    data_train = data_train[split:]
-                    save_pickle(data_dev, pickle_path, "data_dev.pkl")
+                    split = int(len(train_dev_data) * train_dev_split)
+                    data_dev = train_dev_data[: split]
+                    data_train = train_dev_data[split:]
+                    train_set = self.convert_to_dataset(data_train, self.word2index, self.label2index)
+                    dev_set = self.convert_to_dataset(data_dev, self.word2index, self.label2index)
+
+                    save_pickle(dev_set, pickle_path, "data_dev.pkl")
                     print("{} of the training data is split for validation. ".format(train_dev_split))
-                save_pickle(data_train, pickle_path, "data_train.pkl")
+                else:
+                    train_set = self.convert_to_dataset(train_dev_data, self.word2index, self.label2index)
+                save_pickle(train_set, pickle_path, "data_train.pkl")
             else:
-                data_train = load_pickle(pickle_path, "data_train.pkl")
+                train_set = load_pickle(pickle_path, "data_train.pkl")
                 if pickle_exist(pickle_path, "data_dev.pkl"):
-                    data_dev = load_pickle(pickle_path, "data_dev.pkl")
+                    dev_set = load_pickle(pickle_path, "data_dev.pkl")
         else:
             # cross_val is True
             if not pickle_exist(pickle_path, "data_train_0.pkl"):
                 # cross validation
-                data_idx = self.to_index(train_dev_data)
-                data_cv = self.cv_split(data_idx, n_fold)
+                data_cv = self.cv_split(train_dev_data, n_fold)
                 for i, (data_train_cv, data_dev_cv) in enumerate(data_cv):
+                    data_train_cv = self.convert_to_dataset(data_train_cv, self.word2index, self.label2index)
+                    data_dev_cv = self.convert_to_dataset(data_dev_cv, self.word2index, self.label2index)
                     save_pickle(
                         data_train_cv, pickle_path,
                         "data_train_{}.pkl".format(i))
                     save_pickle(
                         data_dev_cv, pickle_path,
                         "data_dev_{}.pkl".format(i))
-                    data_train.append(data_train_cv)
-                    data_dev.append(data_dev_cv)
+                    train_set.append(data_train_cv)
+                    dev_set.append(data_dev_cv)
                 print("{}-fold cross validation.".format(n_fold))
             else:
                 for i in range(n_fold):
                     data_train_cv = load_pickle(pickle_path, "data_train_{}.pkl".format(i))
                     data_dev_cv = load_pickle(pickle_path, "data_dev_{}.pkl".format(i))
-                    data_train.append(data_train_cv)
-                    data_dev.append(data_dev_cv)
+                    train_set.append(data_train_cv)
+                    dev_set.append(data_dev_cv)
 
         # prepare test data if provided
-        data_test = []
+        test_set = []
         if test_data is not None:
             if not pickle_exist(pickle_path, "data_test.pkl"):
-                data_test = self.to_index(test_data)
-                save_pickle(data_test, pickle_path, "data_test.pkl")
+                test_set = self.convert_to_dataset(test_data, self.word2index, self.label2index)
+                save_pickle(test_set, pickle_path, "data_test.pkl")
 
         # return preprocessed results
-        results = [data_train]
+        results = [train_set]
         if cross_val or train_dev_split > 0:
-            results.append(data_dev)
+            results.append(dev_set)
         if test_data:
-            results.append(data_test)
+            results.append(test_set)
         if len(results) == 1:
             return results[0]
         else:
             return tuple(results)
 
     def build_dict(self, data):
-        raise NotImplementedError
+        label2index = DEFAULT_WORD_TO_INDEX.copy()
+        word2index = DEFAULT_WORD_TO_INDEX.copy()
+        for example in data:
+            for word in example[0]:
+                if word not in word2index:
+                    word2index[word] = len(word2index)
+            label = example[1]
+            if isinstance(label, str):
+                # label is a string
+                if label not in label2index:
+                    label2index[label] = len(label2index)
+            elif isinstance(label, list):
+                # label is a list of strings
+                for single_label in label:
+                    if single_label not in label2index:
+                        label2index[single_label] = len(label2index)
+        return word2index, label2index
 
-    def to_index(self, data):
-        raise NotImplementedError
 
     def build_reverse_dict(self, word_dict):
         id2word = {word_dict[w]: w for w in word_dict}
@@ -186,11 +211,23 @@ class BasePreprocess(object):
         return data_train, data_dev
 
     def cv_split(self, data, n_fold):
-        """Split data for cross validation."""
+        """Split data for cross validation.
+
+        :param data: list of string
+        :param n_fold: int
+        :return data_cv:
+
+            ::
+            [
+                (data_train, data_dev),  # 1st fold
+                (data_train, data_dev),  # 2nd fold
+                ...
+            ]
+
+        """
         data_copy = data.copy()
         np.random.shuffle(data_copy)
         fold_size = round(len(data_copy) / n_fold)
-
         data_cv = []
         for i in range(n_fold - 1):
             start = i * fold_size
@@ -202,154 +239,62 @@ class BasePreprocess(object):
         data_dev = data_copy[start:]
         data_train = data_copy[:start]
         data_cv.append((data_train, data_dev))
-
         return data_cv
 
+    def convert_to_dataset(self, data, vocab, label_vocab):
+        """Convert list of indices into a DataSet object.
 
-class SeqLabelPreprocess(BasePreprocess):
-    """Preprocess pipeline, including building mapping from words to index, from index to words,
-        from labels/classes to index, from index to labels/classes.
-        data of three-level list which have multiple labels in each sample.
-        ::
-
-            [
-                [ [word_11, word_12, ...], [label_1, label_1, ...] ],
-                [ [word_21, word_22, ...], [label_2, label_1, ...] ],
-                ...
-            ]
-
-    """
-
-    def __init__(self):
-        super(SeqLabelPreprocess, self).__init__()
-
-    def build_dict(self, data):
-        """Add new words with indices into self.word_dict, new labels with indices into self.label_dict.
-
-        :param data: three-level list
-            ::
-
-            [
-                [ [word_11, word_12, ...], [label_1, label_1, ...] ],
-                [ [word_21, word_22, ...], [label_2, label_1, ...] ],
-                ...
-            ]
-
-        :return word2index: dict of {str, int}
-                label2index: dict of {str, int}
+        :param data: list. Entries are strings.
+        :param vocab: a dict, mapping string (token) to index (int).
+        :param label_vocab: a dict, mapping string (label) to index (int).
+        :return data_set: a DataSet object
         """
-        # In seq labeling, both word seq and label seq need to be padded to the same length in a mini-batch.
-        label2index = DEFAULT_WORD_TO_INDEX.copy()
-        word2index = DEFAULT_WORD_TO_INDEX.copy()
+        use_word_seq = False
+        use_label_seq = False
+        data_set = DataSet()
         for example in data:
-            for word, label in zip(example[0], example[1]):
-                if word not in word2index:
-                    word2index[word] = len(word2index)
-                if label not in label2index:
-                    label2index[label] = len(label2index)
-        return word2index, label2index
+            words, label = example[0], example[1]
+            instance = Instance()
 
-    def to_index(self, data):
-        """Convert word strings and label strings into indices.
+            if isinstance(words, list):
+                x = TextField(words, is_target=False)
+                instance.add_field("word_seq", x)
+                use_word_seq = True
+            else:
+                raise NotImplementedError("words is a {}".format(type(words)))
+
+            if isinstance(label, list):
+                y = TextField(label, is_target=True)
+                instance.add_field("label_seq", y)
+                use_label_seq = True
+            elif isinstance(label, str):
+                y = LabelField(label, is_target=True)
+                instance.add_field("label", y)
+            else:
+                raise NotImplementedError("label is a {}".format(type(label)))
 
-        :param data: three-level list
-            ::
+            data_set.append(instance)
+        if use_word_seq:
+            data_set.index_field("word_seq", vocab)
+        if use_label_seq:
+            data_set.index_field("label_seq", label_vocab)
+        return data_set
 
-            [
-                [ [word_11, word_12, ...], [label_1, label_1, ...] ],
-                [ [word_21, word_22, ...], [label_2, label_1, ...] ],
-                ...
-            ]
 
-        :return data_index: the same shape as data, but each string is replaced by its corresponding index
-        """
-        data_index = []
-        for example in data:
-            word_list = []
-            label_list = []
-            for word, label in zip(example[0], example[1]):
-                word_list.append(self.word2index.get(word, DEFAULT_WORD_TO_INDEX[DEFAULT_UNKNOWN_LABEL]))
-                label_list.append(self.label2index.get(label, DEFAULT_WORD_TO_INDEX[DEFAULT_UNKNOWN_LABEL]))
-            data_index.append([word_list, label_list])
-        return data_index
+class SeqLabelPreprocess(BasePreprocess):
+    def __init__(self):
+        super(SeqLabelPreprocess, self).__init__()
 
 
 class ClassPreprocess(BasePreprocess):
-    """ Preprocess pipeline for classification datasets.
-        Preprocess pipeline, including building mapping from words to index, from index to words,
-        from labels/classes to index, from index to labels/classes.
-        design for data of three-level list which has a single label in each sample.
-            ::
-
-            [
-                [ [word_11, word_12, ...], label_1 ],
-                [ [word_21, word_22, ...], label_2 ],
-                ...
-            ]
-
-    """
-
     def __init__(self):
         super(ClassPreprocess, self).__init__()
 
-    def build_dict(self, data):
-        """Build vocabulary."""
 
-        # build vocabulary from scratch if nothing exists
-        word2index = DEFAULT_WORD_TO_INDEX.copy()
-        label2index = DEFAULT_WORD_TO_INDEX.copy()
-
-        # collect every word and label
-        for sent, label in data:
-            if len(sent) <= 1:
-                continue
-
-            if label not in label2index:
-                label2index[label] = len(label2index)
-
-            for word in sent:
-                if word not in word2index:
-                    word2index[word] = len(word2index)
-        return word2index, label2index
-
-    def to_index(self, data):
-        """Convert word strings and label strings into indices.
-
-        :param data: three-level list
-        ::
-
-            [
-                [ [word_11, word_12, ...], label_1 ],
-                [ [word_21, word_22, ...], label_2 ],
-                ...
-            ]
-
-        :return data_index: the same shape as data, but each string is replaced by its corresponding index
-        """
-        data_index = []
-        for example in data:
-            word_list = []
-            # example[0] is the word list, example[1] is the single label
-            for word in example[0]:
-                word_list.append(self.word2index.get(word, DEFAULT_WORD_TO_INDEX[DEFAULT_UNKNOWN_LABEL]))
-            label_index = self.label2index.get(example[1], DEFAULT_WORD_TO_INDEX[DEFAULT_UNKNOWN_LABEL])
-            data_index.append([word_list, label_index])
-        return data_index
-
-
-def infer_preprocess(pickle_path, data):
-    """Preprocess over inference data. Transform three-level list of strings into that of index.
-        ::
-
-        [
-            [word_11, word_12, ...],
-            [word_21, word_22, ...],
-            ...
-        ]
-
-    """
-    word2index = load_pickle(pickle_path, "word2id.pkl")
-    data_index = []
-    for example in data:
-        data_index.append([word2index.get(w, DEFAULT_UNKNOWN_LABEL) for w in example])
-    return data_index
+if __name__ == "__main__":
+    p = BasePreprocess()
+    train_dev_data = [[["I", "am", "a", "good", "student", "."], "0"],
+                      [["You", "are", "pretty", "."], "1"]
+                      ]
+    training_set = p.run(train_dev_data)
+    print(training_set)
diff --git a/fastNLP/core/tester.py b/fastNLP/core/tester.py
index bcb6ba8c..cfbc918e 100644
--- a/fastNLP/core/tester.py
+++ b/fastNLP/core/tester.py
@@ -2,8 +2,8 @@ import numpy as np
 import torch
 
 from fastNLP.core.action import Action
-from fastNLP.core.action import RandomSampler, Batchifier
-from fastNLP.modules import utils
+from fastNLP.core.action import RandomSampler
+from fastNLP.core.batch import Batch
 from fastNLP.saver.logger import create_logger
 
 logger = create_logger(__name__, "./train_test.log")
@@ -35,16 +35,16 @@ class BaseTester(object):
         """
             "required_args" is the collection of arguments that users must pass to Trainer explicitly. 
             This is used to warn users of essential settings in the training. 
-            Obviously, "required_args" is the subset of "default_args". 
-            The value in "default_args" to the keys in "required_args" is simply for type check. 
+            Specially, "required_args" does not have default value, so they have nothing to do with "default_args".
         """
-        # add required arguments here
-        required_args = {}
+        required_args = {"task"  # one of ("seq_label", "text_classify")
+                         }
 
         for req_key in required_args:
             if req_key not in kwargs:
                 logger.error("Tester lacks argument {}".format(req_key))
                 raise ValueError("Tester lacks argument {}".format(req_key))
+        self._task = kwargs["task"]
 
         for key in default_args:
             if key in kwargs:
@@ -83,10 +83,10 @@ class BaseTester(object):
         self.eval_history.clear()
         self.batch_output.clear()
 
-        iterator = iter(Batchifier(RandomSampler(dev_data), self.batch_size, drop_last=False))
+        data_iterator = Batch(dev_data, self.batch_size, sampler=RandomSampler(), use_cuda=self.use_cuda)
         step = 0
 
-        for batch_x, batch_y in self.make_batch(iterator):
+        for batch_x, batch_y in data_iterator:
             with torch.no_grad():
                 prediction = self.data_forward(network, batch_x)
                 eval_results = self.evaluate(prediction, batch_y)
@@ -112,7 +112,8 @@ class BaseTester(object):
 
     def data_forward(self, network, x):
         """A forward pass of the model. """
-        raise NotImplementedError
+        y = network(**x)
+        return y
 
     def evaluate(self, predict, truth):
         """Compute evaluation metrics.
@@ -121,7 +122,26 @@ class BaseTester(object):
         :param truth: Tensor
         :return eval_results: can be anything. It will be stored in self.eval_history
         """
-        raise NotImplementedError
+        batch_size, max_len = predict.size(0), predict.size(1)
+        if "label_seq" in truth:
+            truth = truth["label_seq"]
+        elif "label" in truth:
+            truth = truth["label"]
+        else:
+            raise NotImplementedError("Unknown key {} in batch_y.".format(truth.keys()))
+        loss = self._model.loss(predict, truth) / batch_size
+
+        prediction = self._model.prediction(predict)
+        # pad prediction to equal length
+        for pred in prediction:
+            if len(pred) < max_len:
+                pred += [0] * (max_len - len(pred))
+        results = torch.Tensor(prediction).view(-1, )
+
+        # make sure "results" is in the same device as "truth"
+        results = results.to(truth)
+        accuracy = torch.sum(results == truth.view((-1,))).to(torch.float) / results.shape[0]
+        return [float(loss), float(accuracy)]
 
     @property
     def metrics(self):
@@ -131,7 +151,9 @@ class BaseTester(object):
 
         :return : variable number of outputs
         """
-        raise NotImplementedError
+        batch_loss = np.mean([x[0] for x in self.eval_history])
+        batch_accuracy = np.mean([x[1] for x in self.eval_history])
+        return batch_loss, batch_accuracy
 
     def show_metrics(self):
         """Customize evaluation outputs in Trainer.
@@ -140,10 +162,8 @@ class BaseTester(object):
 
         :return print_str: str
         """
-        raise NotImplementedError
-
-    def make_batch(self, iterator):
-        raise NotImplementedError
+        loss, accuracy = self.metrics
+        return "dev loss={:.2f}, accuracy={:.2f}".format(loss, accuracy)
 
     def make_eval_output(self, predictions, eval_results):
         """Customize Tester outputs.
@@ -152,78 +172,21 @@ class BaseTester(object):
         :param eval_results: Tensor
         :return: str, to be printed.
         """
-        raise NotImplementedError
+        return self.show_metrics()
+
 
 class SeqLabelTester(BaseTester):
     """Tester for sequence labeling.
 
     """
-
     def __init__(self, **test_args):
         """
         :param test_args: a dict-like object that has __getitem__ method, can be accessed by "test_args["key_str"]"
         """
+        test_args.update({"task": "seq_label"})
+        print(
+            "[FastNLP Warning] SeqLabelTester will be deprecated. Please use Tester with argument 'task'='seq_label'.")
         super(SeqLabelTester, self).__init__(**test_args)
-        self.max_len = None
-        self.mask = None
-        self.seq_len = None
-
-    def data_forward(self, network, inputs):
-        """This is only for sequence labeling with CRF decoder.
-
-        :param network: a PyTorch model
-        :param inputs: tuple of (x, seq_len)
-                        x: Tensor of shape [batch_size, max_len], where max_len is the maximum length of the mini-batch
-                            after padding.
-                        seq_len: list of int, the lengths of sequences before padding.
-        :return y: Tensor of shape [batch_size, max_len]
-        """
-        if not isinstance(inputs, tuple):
-            raise RuntimeError("output_length must be true for sequence modeling.")
-        # unpack the returned value from make_batch
-        x, seq_len = inputs[0], inputs[1]
-        batch_size, max_len = x.size(0), x.size(1)
-        mask = utils.seq_mask(seq_len, max_len)
-        mask = mask.byte().view(batch_size, max_len)
-        if torch.cuda.is_available() and self.use_cuda:
-            mask = mask.cuda()
-        self.mask = mask
-        self.seq_len = seq_len
-        y = network(x)
-        return y
-
-    def evaluate(self, predict, truth):
-        """Compute metrics (or loss).
-
-        :param predict: Tensor, [batch_size, max_len, tag_size]
-        :param truth: Tensor, [batch_size, max_len]
-        :return:
-        """
-        batch_size, max_len = predict.size(0), predict.size(1)
-        loss = self._model.loss(predict, truth, self.mask) / batch_size
-
-        prediction = self._model.prediction(predict, self.mask)
-        results = torch.Tensor(prediction).view(-1, )
-        # make sure "results" is in the same device as "truth"
-        results = results.to(truth)
-        accuracy = torch.sum(results == truth.view((-1,))).to(torch.float) / results.shape[0]
-        return [float(loss), float(accuracy)]
-
-    def metrics(self):
-        batch_loss = np.mean([x[0] for x in self.eval_history])
-        batch_accuracy = np.mean([x[1] for x in self.eval_history])
-        return batch_loss, batch_accuracy
-
-    def show_metrics(self):
-        """This is called by Trainer to print evaluation on dev set.
-
-        :return print_str: str
-        """
-        loss, accuracy = self.metrics()
-        return "dev loss={:.2f}, accuracy={:.2f}".format(loss, accuracy)
-
-    def make_batch(self, iterator):
-        return Action.make_batch(iterator, use_cuda=self.use_cuda, output_length=True)
 
 
 class ClassificationTester(BaseTester):
@@ -236,9 +199,6 @@ class ClassificationTester(BaseTester):
         """
         super(ClassificationTester, self).__init__(**test_args)
 
-    def make_batch(self, iterator, max_len=None):
-        return Action.make_batch(iterator, use_cuda=self.use_cuda, max_len=max_len)
-
     def data_forward(self, network, x):
         """Forward through network."""
         logits = network(x)
diff --git a/fastNLP/core/trainer.py b/fastNLP/core/trainer.py
index 523a1763..f4c3e8c1 100644
--- a/fastNLP/core/trainer.py
+++ b/fastNLP/core/trainer.py
@@ -4,15 +4,14 @@ import time
 from datetime import timedelta
 
 import torch
-import tensorboardX
 from tensorboardX import SummaryWriter
 
 from fastNLP.core.action import Action
-from fastNLP.core.action import RandomSampler, Batchifier
+from fastNLP.core.action import RandomSampler
+from fastNLP.core.batch import Batch
 from fastNLP.core.loss import Loss
 from fastNLP.core.optimizer import Optimizer
 from fastNLP.core.tester import SeqLabelTester, ClassificationTester
-from fastNLP.modules import utils
 from fastNLP.saver.logger import create_logger
 from fastNLP.saver.model_saver import ModelSaver
 
@@ -50,16 +49,16 @@ class BaseTrainer(object):
         """
             "required_args" is the collection of arguments that users must pass to Trainer explicitly. 
             This is used to warn users of essential settings in the training. 
-            Obviously, "required_args" is the subset of "default_args". 
-            The value in "default_args" to the keys in "required_args" is simply for type check. 
+            Specially, "required_args" does not have default value, so they have nothing to do with "default_args".
         """
-        # add required arguments here
-        required_args = {}
+        required_args = {"task"  # one of ("seq_label", "text_classify")
+                         }
 
         for req_key in required_args:
             if req_key not in kwargs:
                 logger.error("Trainer lacks argument {}".format(req_key))
                 raise ValueError("Trainer lacks argument {}".format(req_key))
+        self._task = kwargs["task"]
 
         for key in default_args:
             if key in kwargs:
@@ -90,13 +89,14 @@ class BaseTrainer(object):
         self._optimizer_proto = default_args["optimizer"]
         self._summary_writer = SummaryWriter(self.pickle_path + 'tensorboard_logs')
         self._graph_summaried = False
+        self._best_accuracy = 0.0
 
     def train(self, network, train_data, dev_data=None):
         """General Training Procedure
 
         :param network: a model
-        :param train_data: three-level list, the training set.
-        :param dev_data: three-level list, the validation data (optional)
+        :param train_data: a DataSet instance, the training data
+        :param dev_data: a DataSet instance, the validation data (optional)
         """
         # transfer model to gpu if available
         if torch.cuda.is_available() and self.use_cuda:
@@ -128,7 +128,8 @@ class BaseTrainer(object):
             # turn on network training mode
             self.mode(network, test=False)
             # prepare mini-batch iterator
-            data_iterator = iter(Batchifier(RandomSampler(train_data), self.batch_size, drop_last=False))
+            data_iterator = Batch(train_data, batch_size=self.batch_size, sampler=RandomSampler(),
+                                  use_cuda=self.use_cuda)
             logger.info("prepared data iterator")
 
             # one forward and backward pass
@@ -157,7 +158,7 @@ class BaseTrainer(object):
                 - epoch: int,
         """
         step = 0
-        for batch_x, batch_y in self.make_batch(data_iterator):
+        for batch_x, batch_y in data_iterator:
 
             prediction = self.data_forward(network, batch_x)
 
@@ -166,10 +167,6 @@ class BaseTrainer(object):
             self.update()
             self._summary_writer.add_scalar("loss", loss.item(), global_step=step)
 
-            if not self._graph_summaried:
-                self._summary_writer.add_graph(network, batch_x)
-                self._graph_summaried = True
-
             if kwargs["n_print"] > 0 and step % kwargs["n_print"] == 0:
                 end = time.time()
                 diff = timedelta(seconds=round(end - kwargs["start"]))
@@ -204,9 +201,6 @@ class BaseTrainer(object):
             network_copy = copy.deepcopy(network)
             self.train(network_copy, train_data_cv[i], dev_data_cv[i])
 
-    def make_batch(self, iterator):
-        raise NotImplementedError
-
     def mode(self, network, test):
         Action.mode(network, test)
 
@@ -224,7 +218,12 @@ class BaseTrainer(object):
         self._optimizer.step()
 
     def data_forward(self, network, x):
-        raise NotImplementedError
+        y = network(**x)
+        if not self._graph_summaried:
+            if self._task == "seq_label":
+                self._summary_writer.add_graph(network, (x["word_seq"], x["word_seq_origin_len"]), verbose=False)
+            self._graph_summaried = True
+        return y
 
     def grad_backward(self, loss):
         """Compute gradient with link rules.
@@ -243,6 +242,12 @@ class BaseTrainer(object):
         :param truth: ground truth label vector
         :return: a scalar
         """
+        if "label_seq" in truth:
+            truth = truth["label_seq"]
+        elif "label" in truth:
+            truth = truth["label"]
+        else:
+            raise NotImplementedError("Unknown key {} in batch_y.".format(truth.keys()))
         return self._loss_func(predict, truth)
 
     def define_loss(self):
@@ -270,7 +275,12 @@ class BaseTrainer(object):
         :param validator: a Tester instance
         :return: bool, True means current results on dev set is the best.
         """
-        raise NotImplementedError
+        loss, accuracy = validator.metrics()
+        if accuracy > self._best_accuracy:
+            self._best_accuracy = accuracy
+            return True
+        else:
+            return False
 
     def save_model(self, network, model_name):
         """Save this model with such a name.
@@ -291,55 +301,11 @@ class SeqLabelTrainer(BaseTrainer):
     """Trainer for Sequence Labeling
 
     """
-
     def __init__(self, **kwargs):
+        kwargs.update({"task": "seq_label"})
+        print(
+            "[FastNLP Warning] SeqLabelTrainer will be deprecated. Please use Trainer with argument 'task'='seq_label'.")
         super(SeqLabelTrainer, self).__init__(**kwargs)
-        # self.vocab_size = kwargs["vocab_size"]
-        # self.num_classes = kwargs["num_classes"]
-        self.max_len = None
-        self.mask = None
-        self.best_accuracy = 0.0
-
-    def data_forward(self, network, inputs):
-        if not isinstance(inputs, tuple):
-            raise RuntimeError("output_length must be true for sequence modeling. Receive {}".format(type(inputs[0])))
-        # unpack the returned value from make_batch
-        x, seq_len = inputs[0], inputs[1]
-
-        batch_size, max_len = x.size(0), x.size(1)
-        mask = utils.seq_mask(seq_len, max_len)
-        mask = mask.byte().view(batch_size, max_len)
-
-        if torch.cuda.is_available() and self.use_cuda:
-            mask = mask.cuda()
-        self.mask = mask
-
-        y = network(x)
-        return y
-
-    def get_loss(self, predict, truth):
-        """Compute loss given prediction and ground truth.
-
-        :param predict: prediction label vector, [batch_size, max_len, tag_size]
-        :param truth: ground truth label vector, [batch_size, max_len]
-        :return loss: a scalar
-        """
-        batch_size, max_len = predict.size(0), predict.size(1)
-        assert truth.shape == (batch_size, max_len)
-
-        loss = self._model.loss(predict, truth, self.mask)
-        return loss
-
-    def best_eval_result(self, validator):
-        loss, accuracy = validator.metrics()
-        if accuracy > self.best_accuracy:
-            self.best_accuracy = accuracy
-            return True
-        else:
-            return False
-
-    def make_batch(self, iterator):
-        return Action.make_batch(iterator, output_length=True, use_cuda=self.use_cuda)
 
     def _create_validator(self, valid_args):
         return SeqLabelTester(**valid_args)
@@ -361,9 +327,6 @@ class ClassificationTrainer(BaseTrainer):
         logits = network(x)
         return logits
 
-    def make_batch(self, iterator):
-        return Action.make_batch(iterator, output_length=False, use_cuda=self.use_cuda)
-
     def get_acc(self, y_logit, y_true):
         """Compute accuracy."""
         y_pred = torch.argmax(y_logit, dim=-1)
diff --git a/fastNLP/data/batch.py b/fastNLP/data/batch.py
deleted file mode 100644
index ef5f7d46..00000000
--- a/fastNLP/data/batch.py
+++ /dev/null
@@ -1,86 +0,0 @@
-from collections import defaultdict
-import torch
-
-class Batch(object):
-    def __init__(self, dataset, sampler, batch_size):
-        self.dataset = dataset
-        self.sampler = sampler
-        self.batch_size = batch_size
-
-        self.idx_list = None
-        self.curidx = 0
-
-    def __iter__(self):
-        self.idx_list = self.sampler(self.dataset)
-        self.curidx = 0
-        self.lengths = self.dataset.get_length()
-        return self
-    
-    def __next__(self):
-        if self.curidx >= len(self.idx_list):
-            raise StopIteration
-        else:
-            endidx = min(self.curidx + self.batch_size, len(self.idx_list))
-            padding_length = {field_name : max(field_length[self.curidx: endidx])
-                             for field_name, field_length in self.lengths.items()}
-            
-            batch_x, batch_y = defaultdict(list), defaultdict(list)
-            for idx in range(self.curidx, endidx):
-                x, y = self.dataset.to_tensor(idx, padding_length)
-                for name, tensor in x.items():
-                    batch_x[name].append(tensor)
-                for name, tensor in y.items():
-                    batch_y[name].append(tensor)
-
-            for batch in (batch_x, batch_y):
-                for name, tensor_list in batch.items():
-                    print(name, "   ", tensor_list)
-                    batch[name] = torch.stack(tensor_list, dim=0)
-            self.curidx += endidx
-            return batch_x, batch_y
-            
-
-if __name__ == "__main__":
-    """simple running example
-    """
-    from field import TextField, LabelField
-    from instance import Instance
-    from dataset import DataSet
-
-    texts = ["i am a cat",
-             "this is a test of new batch",
-             "haha"
-            ]
-    labels = [0, 1, 0]
-    
-    # prepare vocabulary
-    vocab = {}
-    for text in texts:
-        for tokens in text.split():
-            if tokens not in vocab:
-                vocab[tokens] = len(vocab)
-
-    # prepare input dataset    
-    data = DataSet()
-    for text, label in zip(texts, labels):
-        x = TextField(text.split(), False)
-        y = LabelField(label, is_target=True)
-        ins = Instance(text=x, label=y)
-        data.append(ins)
-    
-    # use vocabulary to index data
-    data.index_field("text", vocab)
-
-    # define naive sampler for batch class
-    class SeqSampler:
-        def __call__(self, dataset):
-            return list(range(len(dataset)))
-            
-    # use bacth to iterate dataset
-    batcher = Batch(data, SeqSampler(), 2)
-    for epoch in range(3):
-        for batch_x, batch_y in batcher:
-            print(batch_x)
-            print(batch_y)
-            # do stuff
-
diff --git a/fastNLP/data/instance.py b/fastNLP/data/instance.py
deleted file mode 100644
index 4b78dfc3..00000000
--- a/fastNLP/data/instance.py
+++ /dev/null
@@ -1,38 +0,0 @@
-class Instance(object):
-    def __init__(self, **fields):
-        self.fields = fields
-        self.has_index = False
-        self.indexes = {}
-
-    def add_field(self, field_name, field):
-        self.fields[field_name] = field
-    
-    def get_length(self):
-        length = {name : field.get_length() for name, field in self.fields.items()}
-        return length
-
-    def index_field(self, field_name, vocab):
-        """use `vocab` to index certain field
-        """
-        self.indexes[field_name] = self.fields[field_name].index(vocab)
-
-    def index_all(self, vocab):
-        """use `vocab` to index all fields
-        """
-        if self.has_index:
-            print("error")
-            return self.indexes
-        indexes = {name : field.index(vocab) for name, field in self.fields.items()}
-        self.indexes = indexes
-        return indexes
-
-    def to_tensor(self, padding_length: dict):
-        tensorX = {}
-        tensorY = {}
-        for name, field in self.fields.items():
-            if field.is_target:
-                tensorY[name] = field.to_tensor(padding_length[name])
-            else:
-                tensorX[name] = field.to_tensor(padding_length[name])
-            
-        return tensorX, tensorY
diff --git a/fastNLP/models/sequence_modeling.py b/fastNLP/models/sequence_modeling.py
index 5addc73e..bed3f0a6 100644
--- a/fastNLP/models/sequence_modeling.py
+++ b/fastNLP/models/sequence_modeling.py
@@ -4,6 +4,20 @@ from fastNLP.models.base_model import BaseModel
 from fastNLP.modules import decoder, encoder
 
 
+def seq_mask(seq_len, max_len):
+    """Create a mask for the sequences.
+
+    :param seq_len: list or torch.LongTensor
+    :param max_len: int
+    :return mask: torch.LongTensor
+    """
+    if isinstance(seq_len, list):
+        seq_len = torch.LongTensor(seq_len)
+    mask = [torch.ge(seq_len, i + 1) for i in range(max_len)]
+    mask = torch.stack(mask, 1)
+    return mask
+
+
 class SeqLabeling(BaseModel):
     """
     PyTorch Network for sequence labeling
@@ -20,13 +34,17 @@ class SeqLabeling(BaseModel):
         self.Rnn = encoder.lstm.Lstm(word_emb_dim, hidden_dim)
         self.Linear = encoder.linear.Linear(hidden_dim, num_classes)
         self.Crf = decoder.CRF.ConditionalRandomField(num_classes)
+        self.mask = None
 
-    def forward(self, x):
+    def forward(self, word_seq, word_seq_origin_len):
         """
-        :param x: LongTensor, [batch_size, mex_len]
+        :param word_seq: LongTensor, [batch_size, mex_len]
+        :param word_seq_origin_len: LongTensor, [batch_size,], the origin lengths of the sequences.
         :return y: [batch_size, mex_len, tag_size]
         """
-        x = self.Embedding(x)
+        self.mask = self.make_mask(word_seq, word_seq_origin_len)
+
+        x = self.Embedding(word_seq)
         # [batch_size, max_len, word_emb_dim]
         x = self.Rnn(x)
         # [batch_size, max_len, hidden_size * direction]
@@ -34,27 +52,32 @@ class SeqLabeling(BaseModel):
         # [batch_size, max_len, num_classes]
         return x
 
-    def loss(self, x, y, mask):
+    def loss(self, x, y):
         """
         Negative log likelihood loss.
         :param x: Tensor, [batch_size, max_len, tag_size]
         :param y: Tensor, [batch_size, max_len]
-        :param mask: ByteTensor, [batch_size, ,max_len]
         :return loss: a scalar Tensor
 
         """
         x = x.float()
         y = y.long()
-        total_loss = self.Crf(x, y, mask)
+        total_loss = self.Crf(x, y, self.mask)
         return torch.mean(total_loss)
 
-    def prediction(self, x, mask):
+    def make_mask(self, x, seq_len):
+        batch_size, max_len = x.size(0), x.size(1)
+        mask = seq_mask(seq_len, max_len)
+        mask = mask.byte().view(batch_size, max_len)
+        mask = mask.to(x)
+        return mask
+
+    def prediction(self, x):
         """
         :param x: FloatTensor, [batch_size, max_len, tag_size]
-        :param mask: ByteTensor, [batch_size, max_len]
         :return prediction: list of [decode path(list)]
         """
-        tag_seq = self.Crf.viterbi_decode(x, mask)
+        tag_seq = self.Crf.viterbi_decode(x, self.mask)
         return tag_seq
 
 
@@ -81,11 +104,14 @@ class AdvSeqLabel(SeqLabeling):
 
         self.Crf = decoder.CRF.ConditionalRandomField(num_classes)
 
-    def forward(self, x):
+    def forward(self, x, seq_len):
         """
         :param x: LongTensor, [batch_size, mex_len]
+        :param seq_len: list of int.
         :return y: [batch_size, mex_len, tag_size]
         """
+        self.mask = self.make_mask(x, seq_len)
+
         batch_size = x.size(0)
         max_len = x.size(1)
         x = self.Embedding(x)
diff --git a/test/model/seq_labeling.py b/test/model/seq_labeling.py
index 0f7a072b..dcfa8bb4 100644
--- a/test/model/seq_labeling.py
+++ b/test/model/seq_labeling.py
@@ -15,11 +15,11 @@ from fastNLP.core.optimizer import Optimizer
 
 parser = argparse.ArgumentParser()
 parser.add_argument("-s", "--save", type=str, default="./seq_label/", help="path to save pickle files")
-parser.add_argument("-t", "--train", type=str, default="./data_for_tests/people.txt",
+parser.add_argument("-t", "--train", type=str, default="../data_for_tests/people.txt",
                     help="path to the training data")
-parser.add_argument("-c", "--config", type=str, default="./data_for_tests/config", help="path to the config file")
+parser.add_argument("-c", "--config", type=str, default="../data_for_tests/config", help="path to the config file")
 parser.add_argument("-m", "--model_name", type=str, default="seq_label_model.pkl", help="the name of the model")
-parser.add_argument("-i", "--infer", type=str, default="data_for_tests/people_infer.txt",
+parser.add_argument("-i", "--infer", type=str, default="../data_for_tests/people_infer.txt",
                     help="data used for inference")
 
 args = parser.parse_args()
@@ -86,7 +86,7 @@ def train_and_test():
     trainer = SeqLabelTrainer(
         epochs=trainer_args["epochs"],
         batch_size=trainer_args["batch_size"],
-        validate=trainer_args["validate"],
+        validate=False,
         use_cuda=trainer_args["use_cuda"],
         pickle_path=pickle_path,
         save_best_dev=trainer_args["save_best_dev"],
@@ -139,5 +139,5 @@ def train_and_test():
 
 
 if __name__ == "__main__":
-    # train_and_test()
-    infer()
+    train_and_test()
+    # infer()
diff --git a/test/model/text_classify.py b/test/model/text_classify.py
index 6ff3c059..dd20505f 100644
--- a/test/model/text_classify.py
+++ b/test/model/text_classify.py
@@ -115,4 +115,4 @@ def train():
 
 if __name__ == "__main__":
     train()
-    infer()
+    # infer()