diff --git a/fastNLP/action/tester.py b/fastNLP/action/tester.py
index 675537b8..e4cca9e5 100644
--- a/fastNLP/action/tester.py
+++ b/fastNLP/action/tester.py
@@ -2,6 +2,7 @@ import _pickle
 
 import numpy as np
 import torch
+import os
 
 from fastNLP.action.action import Action
 from fastNLP.action.action import RandomSampler, Batchifier
@@ -174,3 +175,153 @@ class POSTester(BaseTester):
         """
         loss, accuracy = self.matrices()
         return "dev loss={:.2f}, accuracy={:.2f}".format(loss, accuracy)
+
+
+class ClassTester(BaseTester):
+    """Tester for classification."""
+
+    def __init__(self, test_args):
+        """
+        :param test_args: a dict-like object that has __getitem__ method, \
+            can be accessed by "test_args["key_str"]"
+        """
+        # super(ClassTester, self).__init__()
+        self.pickle_path = test_args["pickle_path"]
+
+        self.save_dev_data = None
+        self.output = None
+        self.mean_loss = None
+        self.iterator = None
+
+        if "test_name" in test_args:
+            self.test_name = test_args["test_name"]
+        else:
+            self.test_name = "data_test.pkl"
+
+        if "validate_in_training" in test_args:
+            self.validate_in_training = test_args["validate_in_training"]
+        else:
+            self.validate_in_training = False
+
+        if "save_output" in test_args:
+            self.save_output = test_args["save_output"]
+        else:
+            self.save_output = False
+
+        if "save_loss" in test_args:
+            self.save_loss = test_args["save_loss"]
+        else:
+            self.save_loss = True
+
+        if "batch_size" in test_args:
+            self.batch_size = test_args["batch_size"]
+        else:
+            self.batch_size = 50
+        if "use_cuda" in test_args:
+            self.use_cuda = test_args["use_cuda"]
+        else:
+            self.use_cuda = True
+
+        if "max_len" in test_args:
+            self.max_len = test_args["max_len"]
+        else:
+            self.max_len = None
+
+        self.model = None
+        self.eval_history = []
+        self.batch_output = []
+
+    def test(self, network):
+        # prepare model
+        if torch.cuda.is_available() and self.use_cuda:
+            self.model = network.cuda()
+        else:
+            self.model = network
+
+        # no backward setting for model
+        for param in self.model.parameters():
+            param.requires_grad = False
+
+        # turn on the testing mode; clean up the history
+        self.mode(network, test=True)
+
+        # prepare test data
+        data_test = self.prepare_input(self.pickle_path, self.test_name)
+
+        # data generator
+        self.iterator = iter(Batchifier(
+            RandomSampler(data_test), self.batch_size, drop_last=False))
+
+        # test
+        n_batches = len(data_test) // self.batch_size
+        n_print = n_batches // 10
+        step = 0
+        for batch_x, batch_y in self.batchify(data_test, max_len=self.max_len):
+            prediction = self.data_forward(network, batch_x)
+            eval_results = self.evaluate(prediction, batch_y)
+
+            if self.save_output:
+                self.batch_output.append(prediction)
+            if self.save_loss:
+                self.eval_history.append(eval_results)
+
+            if step % n_print == 0:
+                print("step: {:>5}".format(step))
+
+            step += 1
+
+    def prepare_input(self, data_dir, file_name):
+        """Prepare data."""
+        file_path = os.path.join(data_dir, file_name)
+        with open(file_path, 'rb') as f:
+            data = _pickle.load(f)
+        return data
+
+    def batchify(self, data, max_len=None):
+        """Batch and pad data."""
+        for indices in self.iterator:
+            # generate batch and pad
+            batch = [data[idx] for idx in indices]
+            batch_x = [sample[0] for sample in batch]
+            batch_y = [sample[1] for sample in batch]
+            batch_x = self.pad(batch_x)
+
+            # convert to tensor
+            batch_x = torch.tensor(batch_x, dtype=torch.long)
+            batch_y = torch.tensor(batch_y, dtype=torch.long)
+            if torch.cuda.is_available() and self.use_cuda:
+                batch_x = batch_x.cuda()
+                batch_y = batch_y.cuda()
+
+            # trim data to max_len
+            if max_len is not None and batch_x.size(1) > max_len:
+                batch_x = batch_x[:, :max_len]
+
+            yield batch_x, batch_y
+
+    def data_forward(self, network, x):
+        """Forward through network."""
+        logits = network(x)
+        return logits
+
+    def evaluate(self, y_logit, y_true):
+        """Return y_pred and y_true."""
+        y_prob = torch.nn.functional.softmax(y_logit, dim=-1)
+        return [y_prob, y_true]
+
+    def matrices(self):
+        """Compute accuracy."""
+        y_prob, y_true = zip(*self.eval_history)
+        y_prob = torch.cat(y_prob, dim=0)
+        y_pred = torch.argmax(y_prob, dim=-1)
+        y_true = torch.cat(y_true, dim=0)
+        acc = float(torch.sum(y_pred == y_true)) / len(y_true)
+        return y_true.cpu().numpy(), y_prob.cpu().numpy(), acc
+
+    def mode(self, model, test=True):
+        """To do: combine this function with Trainer ?? """
+        if test:
+            model.eval()
+        else:
+            model.train()
+        self.eval_history.clear()
diff --git a/fastNLP/action/trainer.py b/fastNLP/action/trainer.py
index f1409b3d..7162a065 100644
--- a/fastNLP/action/trainer.py
+++ b/fastNLP/action/trainer.py
@@ -2,6 +2,10 @@ import _pickle
 
 import numpy as np
 import torch
+import torch.nn as nn
+import os
+from time import time
+from datetime import timedelta
 
 from fastNLP.action.action import Action
 from fastNLP.action.action import RandomSampler, Batchifier
@@ -392,6 +396,201 @@ class POSTrainer(BaseTrainer):
         return loss
 
 
+class ClassTrainer(BaseTrainer):
+    """Trainer for classification."""
+
+    def __init__(self, train_args):
+        # super(ClassTrainer, self).__init__(train_args)
+        self.n_epochs = train_args["epochs"]
+        self.batch_size = train_args["batch_size"]
+        self.pickle_path = train_args["pickle_path"]
+
+        if "validate" in train_args:
+            self.validate = train_args["validate"]
+        else:
+            self.validate = False
+        if "learn_rate" in train_args:
+            self.learn_rate = train_args["learn_rate"]
+        else:
+            self.learn_rate = 1e-3
+        if "momentum" in train_args:
+            self.momentum = train_args["momentum"]
+        else:
+            self.momentum = 0.9
+        if "use_cuda" in train_args:
+            self.use_cuda = train_args["use_cuda"]
+        else:
+            self.use_cuda = True
+
+        self.model = None
+        self.iterator = None
+        self.loss_func = None
+        self.optimizer = None
+
+    def train(self, network):
+        """General Training Steps
+        :param network: a model
+
+        The method is framework independent.
+        Work by calling the following methods:
+            - prepare_input
+            - mode
+            - define_optimizer
+            - data_forward
+            - get_loss
+            - grad_backward
+            - update
+        Subclasses must implement these methods with a specific framework.
+        """
+        # prepare model and data, transfer model to gpu if available
+        if torch.cuda.is_available() and self.use_cuda:
+            self.model = network.cuda()
+        else:
+            self.model = network
+        data_train, data_dev, data_test, embedding = self.prepare_input(
+            self.pickle_path)
+
+        # define tester over dev data
+        # valid_args = {
+        #     "save_output": True, "validate_in_training": True,
+        #     "save_dev_input": True, "save_loss": True,
+        #     "batch_size": self.batch_size, "pickle_path": self.pickle_path}
+        # validator = POSTester(valid_args)
+
+        # urn on network training mode, define loss and optimizer
+        self.define_loss()
+        self.define_optimizer()
+        self.mode(test=False)
+
+        # main training epochs
+        start = time()
+        n_samples = len(data_train)
+        n_batches = n_samples // self.batch_size
+        n_print = n_batches // 10
+        for epoch in range(self.n_epochs):
+            # prepare batch iterator
+            self.iterator = iter(Batchifier(
+                RandomSampler(data_train), self.batch_size, drop_last=False))
+
+            # training iterations in one epoch
+            step = 0
+            for batch_x, batch_y in self.batchify(data_train):
+                prediction = self.data_forward(network, batch_x)
+
+                loss = self.get_loss(prediction, batch_y)
+                self.grad_backward(loss)
+                self.update()
+
+                if step % n_print == 0:
+                    acc = self.get_acc(prediction, batch_y)
+                    end = time()
+                    diff = timedelta(seconds=round(end - start))
+                    print("epoch: {:>3} step: {:>4} loss: {:>4.2}"
+                          " train acc: {:>5.1%} time: {}".format(
+                              epoch, step, loss, acc, diff))
+
+                step += 1
+
+            # if self.validate:
+            #     if data_dev is None:
+            #         raise RuntimeError("No validation data provided.")
+            #     validator.test(network)
+            #     print("[epoch {}]".format(epoch), end=" ")
+            #     print(validator.show_matrices())
+
+        # finish training
+
+    def prepare_input(self, data_path):
+        """
+            To do: Load pkl files of train/dev/test and embedding
+        """
+
+        names = [
+            "data_train.pkl", "data_dev.pkl",
+            "data_test.pkl", "embedding.pkl"]
+
+        files = []
+        for name in names:
+            file_path = os.path.join(data_path, name)
+            if os.path.exists(file_path):
+                with open(file_path, 'rb') as f:
+                    data = _pickle.load(f)
+            else:
+                data = []
+            files.append(data)
+
+        return tuple(files)
+
+    def mode(self, test=False):
+        """
+        Tell the network to be trained or not.
+        :param test: bool
+        """
+        if test:
+            self.model.eval()
+        else:
+            self.model.train()
+
+    def define_loss(self):
+        """
+            Assign an instance of loss function to self.loss_func
+            E.g. self.loss_func = nn.CrossEntropyLoss()
+        """
+        if self.loss_func is None:
+            if hasattr(self.model, "loss"):
+                self.loss_func = self.model.loss
+            else:
+                self.loss_func = nn.CrossEntropyLoss()
+
+    def define_optimizer(self):
+        """
+        Define framework-specific optimizer specified by the models.
+        """
+        self.optimizer = torch.optim.SGD(
+            self.model.parameters(),
+            lr=self.learn_rate,
+            momentum=self.momentum)
+
+    def data_forward(self, network, x):
+        """Forward through network."""
+        logits = network(x)
+        return logits
+
+    def get_loss(self, predict, truth):
+        """Calculate loss."""
+        return self.loss_func(predict, truth)
+
+    def grad_backward(self, loss):
+        """Compute gradient backward."""
+        self.model.zero_grad()
+        loss.backward()
+
+    def update(self):
+        """Apply gradient."""
+        self.optimizer.step()
+
+    def batchify(self, data):
+        """Batch and pad data."""
+        for indices in self.iterator:
+            batch = [data[idx] for idx in indices]
+            batch_x = [sample[0] for sample in batch]
+            batch_y = [sample[1] for sample in batch]
+            batch_x = self.pad(batch_x)
+
+            batch_x = torch.tensor(batch_x, dtype=torch.long)
+            batch_y = torch.tensor(batch_y, dtype=torch.long)
+            if torch.cuda.is_available() and self.use_cuda:
+                batch_x = batch_x.cuda()
+                batch_y = batch_y.cuda()
+
+            yield batch_x, batch_y
+
+    def get_acc(self, y_logit, y_true):
+        """Compute accuracy."""
+        y_pred = torch.argmax(y_logit, dim=-1)
+        return int(torch.sum(y_true == y_pred)) / len(y_true)
+
+
 if __name__ == "__name__":
     train_args = {"epochs": 1, "validate": False, "batch_size": 3, "pickle_path": "./"}
     trainer = BaseTrainer(train_args)
diff --git a/fastNLP/loader/dataset_loader.py b/fastNLP/loader/dataset_loader.py
index d57a48db..a67249f5 100644
--- a/fastNLP/loader/dataset_loader.py
+++ b/fastNLP/loader/dataset_loader.py
@@ -29,11 +29,11 @@ class POSDatasetLoader(DatasetLoader):
         return lines
 
 
-class ClassificationDatasetLoader(DatasetLoader):
-    """loader for classfication data sets"""
+class ClassDatasetLoader(DatasetLoader):
+    """Loader for classification data sets"""
 
     def __init__(self, data_name, data_path):
-        super(ClassificationDatasetLoader, data_name).__init__()
+        super(ClassDatasetLoader, self).__init__(data_name, data_path)
 
     def load(self):
         assert os.path.exists(self.data_path)
@@ -44,16 +44,21 @@ class ClassificationDatasetLoader(DatasetLoader):
     @staticmethod
     def parse(lines):
         """
-        :param lines: lines from dataset
-        :return: list(list(list())): the three level of lists are
+        Params
+            lines: lines from dataset
+        Return
+            list(list(list())): the three level of lists are
                 words, sentence, and dataset
         """
         dataset = list()
         for line in lines:
-            label = line.split(" ")[0]
-            words = line.split(" ")[1:]
-            word = list([w for w in words])
-            sentence = list([word, label])
+            line = line.strip().split()
+            label = line[0]
+            words = line[1:]
+            if len(words) <= 1:
+                continue
+
+            sentence = [words, label]
             dataset.append(sentence)
         return dataset
 
diff --git a/fastNLP/loader/preprocess.py b/fastNLP/loader/preprocess.py
index 8b9c6d88..c977916e 100644
--- a/fastNLP/loader/preprocess.py
+++ b/fastNLP/loader/preprocess.py
@@ -198,4 +198,189 @@ class POSPreprocess(BasePreprocess):
         pass
 
     def data_test(self):
-        pass
\ No newline at end of file
+        pass
+
+
+class ClassPreprocess(BasePreprocess):
+    """
+    Pre-process the classification datasets.
+
+    Params:
+        pickle_path - directory to save result of pre-processing
+    Saves:
+        word2id.pkl
+        id2word.pkl
+        class2id.pkl
+        id2class.pkl
+        embedding.pkl
+        data_train.pkl
+        data_dev.pkl
+        data_test.pkl
+    """
+
+    def __init__(self, pickle_path):
+        # super(ClassPreprocess, self).__init__(data, pickle_path)
+        self.word_dict = None
+        self.label_dict = None
+        self.pickle_path = pickle_path  # save directory
+
+    def process(self, data, save_name):
+        """
+        Process data.
+
+        Params:
+            data - nested list, data = [sample1, sample2, ...],
+                sample = [sentence, label], sentence = [word1, word2, ...]
+            save_name - name of processed data, such as data_train.pkl
+        Returns:
+            vocab_size - vocabulary size
+            n_classes - number of classes
+        """
+        self.build_dict(data)
+        self.word2id()
+        vocab_size = self.id2word()
+        self.class2id()
+        num_classes = self.id2class()
+        self.embedding()
+        self.data_generate(data, save_name)
+
+        return vocab_size, num_classes
+
+    def build_dict(self, data):
+        """Build vocabulary."""
+
+        # just read if word2id.pkl and class2id.pkl exists
+        if self.pickle_exist("word2id.pkl") and \
+                self.pickle_exist("class2id.pkl"):
+            file_name = os.path.join(self.pickle_path, "word2id.pkl")
+            with open(file_name, 'rb') as f:
+                self.word_dict = _pickle.load(f)
+            file_name = os.path.join(self.pickle_path, "class2id.pkl")
+            with open(file_name, 'rb') as f:
+                self.label_dict = _pickle.load(f)
+            return
+
+        # build vocabulary from scratch if nothing exists
+        self.word_dict = {
+            DEFAULT_PADDING_LABEL: 0,
+            DEFAULT_UNKNOWN_LABEL: 1,
+            DEFAULT_RESERVED_LABEL[0]: 2,
+            DEFAULT_RESERVED_LABEL[1]: 3,
+            DEFAULT_RESERVED_LABEL[2]: 4}
+        self.label_dict = {}
+
+        # collect every word and label
+        for sent, label in data:
+            if len(sent) <= 1:
+                continue
+
+            if label not in self.label_dict:
+                index = len(self.label_dict)
+                self.label_dict[label] = index
+
+            for word in sent:
+                if word not in self.word_dict:
+                    index = len(self.word_dict)
+                    self.word_dict[word[0]] = index
+
+    def pickle_exist(self, pickle_name):
+        """
+        Check whether a pickle file exists.
+
+        Params
+            pickle_name: the filename of target pickle file
+        Return
+            True if file exists else False
+        """
+        if not os.path.exists(self.pickle_path):
+            os.makedirs(self.pickle_path)
+        file_name = os.path.join(self.pickle_path, pickle_name)
+        if os.path.exists(file_name):
+            return True
+        else:
+            return False
+
+    def word2id(self):
+        """Save vocabulary of {word:id} mapping format."""
+        # nothing will be done if word2id.pkl exists
+        if self.pickle_exist("word2id.pkl"):
+            return
+
+        file_name = os.path.join(self.pickle_path, "word2id.pkl")
+        with open(file_name, "wb") as f:
+            _pickle.dump(self.word_dict, f)
+
+    def id2word(self):
+        """Save vocabulary of {id:word} mapping format."""
+        # nothing will be done if id2word.pkl exists
+        if self.pickle_exist("id2word.pkl"):
+            file_name = os.path.join(self.pickle_path, "id2word.pkl")
+            with open(file_name, 'rb') as f:
+                id2word_dict = _pickle.load(f)
+            return len(id2word_dict)
+
+        id2word_dict = {self.word_dict[w]: w for w in self.word_dict}
+        file_name = os.path.join(self.pickle_path, "id2word.pkl")
+        with open(file_name, "wb") as f:
+            _pickle.dump(id2word_dict, f)
+        return len(id2word_dict)
+
+    def class2id(self):
+        """Save mapping of {class:id}."""
+        # nothing will be done if class2id.pkl exists
+        if self.pickle_exist("class2id.pkl"):
+            return
+
+        file_name = os.path.join(self.pickle_path, "class2id.pkl")
+        with open(file_name, "wb") as f:
+            _pickle.dump(self.label_dict, f)
+
+    def id2class(self):
+        """Save mapping of {id:class}."""
+        # nothing will be done if id2class.pkl exists
+        if self.pickle_exist("id2class.pkl"):
+            file_name = os.path.join(self.pickle_path, "id2class.pkl")
+            with open(file_name, "rb") as f:
+                id2class_dict = _pickle.load(f)
+            return len(id2class_dict)
+
+        id2class_dict = {self.label_dict[c]: c for c in self.label_dict}
+        file_name = os.path.join(self.pickle_path, "id2class.pkl")
+        with open(file_name, "wb") as f:
+            _pickle.dump(id2class_dict, f)
+        return len(id2class_dict)
+
+    def embedding(self):
+        """Save embedding lookup table corresponding to vocabulary."""
+        # nothing will be done if embedding.pkl exists
+        if self.pickle_exist("embedding.pkl"):
+            return
+
+        # retrieve vocabulary from pre-trained embedding (not implemented)
+
+    def data_generate(self, data_src, save_name):
+        """Convert dataset from text to digit."""
+
+        # nothing will be done if file exists
+        save_path = os.path.join(self.pickle_path, save_name)
+        if os.path.exists(save_path):
+            return
+
+        data = []
+        # for every sample
+        for sent, label in data_src:
+            if len(sent) <= 1:
+                continue
+
+            label_id = self.label_dict[label]  # label id
+            sent_id = []  # sentence ids
+            for word in sent:
+                if word in self.word_dict:
+                    sent_id.append(self.word_dict[word])
+                else:
+                    sent_id.append(self.word_dict[DEFAULT_UNKNOWN_LABEL])
+            data.append([sent_id, label_id])
+
+        # save data
+        with open(save_path, "wb") as f:
+            _pickle.dump(data, f)
diff --git a/fastNLP/models/cnn_text_classification.py b/fastNLP/models/cnn_text_classification.py
new file mode 100644
index 00000000..76a6cd97
--- /dev/null
+++ b/fastNLP/models/cnn_text_classification.py
@@ -0,0 +1,37 @@
+# python: 3.6
+# encoding: utf-8
+
+import torch.nn as nn
+# import torch.nn.functional as F
+from fastNLP.models.base_model import BaseModel
+from fastNLP.modules.encoder.conv_maxpool import ConvMaxpool
+
+
+class CNNText(BaseModel):
+    """
+    Text classification model by character CNN, the implementation of paper
+    'Yoon Kim. 2014. Convolution Neural Networks for Sentence
+    Classification.'
+    """
+
+    def __init__(self, class_num=9,
+                 kernel_nums=[100, 100, 100], kernel_sizes=[3, 4, 5],
+                 embed_num=1000, embed_dim=300, pretrained_embed=None,
+                 drop_prob=0.5):
+        super(CNNText, self).__init__()
+
+        # no support for pre-trained embedding currently
+        self.embed = nn.Embedding(embed_num, embed_dim, padding_idx=0)
+        self.conv_pool = ConvMaxpool(
+            in_channels=embed_dim,
+            out_channels=kernel_nums,
+            kernel_sizes=kernel_sizes)
+        self.dropout = nn.Dropout(drop_prob)
+        self.fc = nn.Linear(sum(kernel_nums), class_num)
+
+    def forward(self, x):
+        x = self.embed(x)  # [N,L] -> [N,L,C]
+        x = self.conv_pool(x)  # [N,L,C] -> [N,C]
+        x = self.dropout(x)
+        x = self.fc(x)  # [N,C] -> [N, N_class]
+        return x
diff --git a/fastNLP/modules/encoder/conv_maxpool.py b/fastNLP/modules/encoder/conv_maxpool.py
new file mode 100644
index 00000000..0012dce7
--- /dev/null
+++ b/fastNLP/modules/encoder/conv_maxpool.py
@@ -0,0 +1,53 @@
+# python: 3.6
+# encoding: utf-8
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+
+
+class ConvMaxpool(nn.Module):
+    """
+    Convolution and max-pooling module with multiple kernel sizes.
+    """
+
+    def __init__(self, in_channels, out_channels, kernel_sizes,
+                 stride=1, padding=0, dilation=1,
+                 groups=1, bias=True, activation='relu'):
+        super(ConvMaxpool, self).__init__()
+
+        # convolution
+        if isinstance(kernel_sizes, (list, tuple, int)):
+            if isinstance(kernel_sizes, int):
+                out_channels = [out_channels]
+                kernel_sizes = [kernel_sizes]
+            self.convs = nn.ModuleList([nn.Conv1d(
+                in_channels=in_channels,
+                out_channels=oc,
+                kernel_size=ks,
+                stride=stride,
+                padding=padding,
+                dilation=dilation,
+                groups=groups,
+                bias=bias)
+                for oc, ks in zip(out_channels, kernel_sizes)])
+        else:
+            raise Exception(
+                'Incorrect kernel sizes: should be list, tuple or int')
+
+        # activation function
+        if activation == 'relu':
+            self.activation = F.relu
+        else:
+            raise Exception(
+                "Undefined activation function: choose from: relu")
+
+    def forward(self, x):
+        # [N,L,C] -> [N,C,L]
+        x = torch.transpose(x, 1, 2)
+        # convolution
+        xs = [self.activation(conv(x)) for conv in self.convs]  # [[N,C,L]]
+        # max-pooling
+        xs = [F.max_pool1d(input=i, kernel_size=i.size(2)).squeeze(2)
+              for i in xs]  # [[N, C]]
+        return torch.cat(xs, dim=-1)  # [N,C]