diff --git a/fastNLP/api/parser.py b/fastNLP/api/parser.py
index 67bcca4f..79c070d6 100644
--- a/fastNLP/api/parser.py
+++ b/fastNLP/api/parser.py
@@ -5,6 +5,8 @@ from fastNLP.api.pipeline import Pipeline
 from fastNLP.api.processor import *
 from fastNLP.models.biaffine_parser import BiaffineParser
 
+import torch
+
 
 class DependencyParser(API):
     def __init__(self):
@@ -18,19 +20,35 @@ class DependencyParser(API):
 
         pred = Predictor()
         res = pred.predict(self.model, dataset)
+        heads, head_tags = [], []
+        for batch in res:
+            heads.append(batch['heads'])
+            head_tags.append(batch['labels'])
+        heads, head_tags = torch.cat(heads, dim=0), torch.cat(head_tags, dim=0)
+        return heads, head_tags
 
-        return res
 
     def build(self):
-        pipe = Pipeline()
-
-        # build pipeline
+        BOS = '<BOS>'
+        NUM = '<NUM>'
+        model_args = {}
+        load_path = ''
+        word_vocab = load(f'{load_path}/word_v.pkl')
+        pos_vocab = load(f'{load_path}/pos_v.pkl')
         word_seq = 'word_seq'
         pos_seq = 'pos_seq'
-        pipe.add_processor(Num2TagProcessor('<NUM>', 'raw_sentence', word_seq))
+
+        pipe = Pipeline()
+        # build pipeline
+        pipe.add_processor(Num2TagProcessor(NUM, 'raw_sentence', word_seq))
+        pipe.add_processor(MapFieldProcessor(lambda x: [BOS] + x, word_seq, None))
+        pipe.add_processor(MapFieldProcessor(lambda x: [BOS] + x, pos_seq, None))
         pipe.add_processor(IndexerProcessor(word_vocab, word_seq, word_seq+'_idx'))
         pipe.add_processor(IndexerProcessor(pos_vocab, pos_seq, pos_seq+'_idx'))
+        pipe.add_processor(MapFieldProcessor(lambda x: len(x), word_seq, 'seq_len'))
+
 
         # load model parameters
-        self.model = BiaffineParser()
+        self.model = BiaffineParser(**model_args)
         self.pipeline = pipe
+
diff --git a/fastNLP/api/processor.py b/fastNLP/api/processor.py
index 109aa7b6..97e9b1b2 100644
--- a/fastNLP/api/processor.py
+++ b/fastNLP/api/processor.py
@@ -145,7 +145,6 @@ class IndexerProcessor(Processor):
 
 class VocabProcessor(Processor):
     def __init__(self, field_name):
-
         super(VocabProcessor, self).__init__(field_name, None)
         self.vocab = Vocabulary()
 
@@ -172,3 +171,15 @@ class SeqLenProcessor(Processor):
             ins[self.new_added_field_name] = length
         dataset.set_need_tensor(**{self.new_added_field_name: True})
         return dataset
+
+class Index2WordProcessor(Processor):
+    def __init__(self, vocab, field_name, new_added_field_name):
+        super(Index2WordProcessor, self).__init__(field_name, new_added_field_name)
+        self.vocab = vocab
+
+    def process(self, dataset):
+        for ins in dataset:
+            new_sent = [self.vocab.to_word(w) for w in ins[self.field_name]]
+            ins[self.new_added_field_name] = new_sent
+        return dataset
+
diff --git a/fastNLP/models/base_model.py b/fastNLP/models/base_model.py
index c73bdfd9..59605f4f 100644
--- a/fastNLP/models/base_model.py
+++ b/fastNLP/models/base_model.py
@@ -13,3 +13,6 @@ class BaseModel(torch.nn.Module):
     def fit(self, train_data, dev_data=None, **train_args):
         trainer = Trainer(**train_args)
         trainer.train(self, train_data, dev_data)
+
+    def predict(self):
+        pass
diff --git a/fastNLP/models/biaffine_parser.py b/fastNLP/models/biaffine_parser.py
index 7e0a9cec..37070e1b 100644
--- a/fastNLP/models/biaffine_parser.py
+++ b/fastNLP/models/biaffine_parser.py
@@ -9,6 +9,7 @@ from torch.nn import functional as F
 from fastNLP.modules.utils import initial_parameter
 from fastNLP.modules.encoder.variational_rnn import VarLSTM
 from fastNLP.modules.dropout import TimestepDropout
+from fastNLP.models.base_model import BaseModel
 
 def mst(scores):
     """
@@ -113,7 +114,7 @@ def _find_cycle(vertices, edges):
     return [SCC for SCC in _SCCs if len(SCC) > 1]
 
 
-class GraphParser(nn.Module):
+class GraphParser(BaseModel):
     """Graph based Parser helper class, support greedy decoding and MST(Maximum Spanning Tree) decoding
     """
     def __init__(self):
@@ -370,4 +371,20 @@ class BiaffineParser(GraphParser):
         label_nll = -(label_loss*float_mask).mean()
         return arc_nll + label_nll
 
+    def predict(self, word_seq, pos_seq, word_seq_origin_len):
+        """
 
+        :param word_seq:
+        :param pos_seq:
+        :param word_seq_origin_len:
+        :return: head_pred: [B, L]
+                 label_pred: [B, L]
+                 seq_len: [B,]
+        """
+        res = self(word_seq, pos_seq, word_seq_origin_len)
+        output = {}
+        output['head_pred'] = res.pop('head_pred')
+        _, label_pred = res.pop('label_pred').max(2)
+        output['label_pred'] = label_pred
+        output['seq_len'] = word_seq_origin_len
+        return output
diff --git a/test/core/test_batch.py b/test/core/test_batch.py
index 826167ac..6418cd99 100644
--- a/test/core/test_batch.py
+++ b/test/core/test_batch.py
@@ -30,11 +30,13 @@ class TestCase1(unittest.TestCase):
         for text, label in zip(texts, labels):
             x = TextField(text, is_target=False)
             y = LabelField(label, is_target=True)
-            ins = Instance(text=x, label=y)
+            ins = Instance(raw_text=x, label=y)
             data.append(ins)
 
         # use vocabulary to index data
-        data.index_field("text", vocab)
+        # data.index_field("text", vocab)
+        for ins in data:
+            ins['text'] = [vocab.to_index(w) for w in ins['raw_text']]
 
         # define naive sampler for batch class
         class SeqSampler: