diff --git a/dssm/infer.py b/dssm/infer.py
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/dssm/network_conf.py b/dssm/network_conf.py
new file mode 100644
index 0000000000000000000000000000000000000000..be3e84a9131904dea2224c02bf9df2f8d7e4e455
--- /dev/null
+++ b/dssm/network_conf.py
@@ -0,0 +1,217 @@
+from paddle import v2 as paddle
+from paddle.v2.attr import ParamAttr
+from utils import TaskType, logger
+
+
+class DSSM(object):
+    def __init__(self,
+                 dnn_dims=[],
+                 vocab_sizes=[],
+                 task_type=TaskType.CLASSFICATION,
+                 share_semantic_generator=False,
+                 class_num=None,
+                 share_embed=False):
+        '''
+        @dnn_dims: list of int
+            dimentions of each layer in semantic vector generator.
+        @vocab_sizes: 2-d tuple
+            size of both left and right items.
+        @task_type: str
+            type of task, should be 'rank', 'regression' or 'classification'
+        @share_semantic_generator: bool
+            whether to share the semantic vector generator for both left and right.
+        @share_embed: bool
+            whether to share the embeddings between left and right.
+        @class_num: int
+            number of categories.
+        '''
+        assert len(
+            vocab_sizes
+        ) == 2, "vocab_sizes specify the sizes left and right inputs, and dim should be 2."
+
+        self.dnn_dims = dnn_dims
+        self.vocab_sizes = vocab_sizes
+        self.share_semantic_generator = share_semantic_generator
+        self.share_embed = share_embed
+        self.task_type = task_type
+        self.class_num = class_num
+
+        logger.info("vocabulary sizes: %s" % str(self.vocab_sizes))
+
+    def __call__(self):
+        if self.task_type == TaskType.CLASSFICATION:
+            return self._build_classification_model()
+        return self._build_rank_model()
+
+    def create_embedding(self, input, prefix=''):
+        '''
+        Create an embedding table whose name has a `prefix`.
+        '''
+        emb = paddle.layer.embedding(
+            input=input,
+            size=self.dnn_dims[0],
+            param_attr=ParamAttr(name='%s_emb.w' % prefix))
+        return emb
+
+    def create_fc(self, emb, prefix=''):
+        '''
+        A multi-layer fully connected neural networks.
+
+        @emb: paddle.layer
+            output of the embedding layer
+        @prefix: str
+            prefix of layers' names, used to share parameters between more than one `fc` parts.
+        '''
+        _input_layer = paddle.layer.pooling(
+            input=emb, pooling_type=paddle.pooling.Max())
+        for id, dim in enumerate(self.dnn_dims[1:]):
+            name = "%s_fc_%d_%d" % (prefix, id, dim)
+            fc = paddle.layer.fc(
+                name=name,
+                input=_input_layer,
+                size=dim,
+                act=paddle.activation.Relu(),
+                param_attr=ParamAttr(name='%s.w' % name),
+                bias_attr=None, )
+            _input_layer = fc
+        return _input_layer
+
+    def create_cnn(self, emb, prefix=''):
+        '''
+        A multi-layer CNN.
+
+        @emb: paddle.layer
+            output of the embedding layer
+        @prefix: str
+            prefix of layers' names, used to share parameters between more than one `cnn` parts.
+        '''
+        pass
+
+    def _build_classification_model(self):
+        '''
+        Build a classification model, and the cost is returned.
+
+        A Classification has 3 inputs:
+          - source sentence
+          - target sentence
+          - classification label
+
+        '''
+        # prepare inputs.
+        assert self.class_num
+
+        source = paddle.layer.data(
+            name='source_input',
+            type=paddle.data_type.integer_value_sequence(self.vocab_sizes[0]))
+        target = paddle.layer.data(
+            name='target_input',
+            type=paddle.data_type.integer_value_sequence(self.vocab_sizes[1]))
+        label = paddle.layer.data(
+            name='label_input',
+            type=paddle.data_type.integer_value(self.class_num))
+
+        prefixs = '_ _'.split(
+        ) if self.share_semantic_generator else 'left right'.split()
+        embed_prefixs = '_ _'.split(
+        ) if self.share_embed else 'left right'.split()
+
+        word_vecs = []
+        for id, input in enumerate([source, target]):
+            x = self.create_embedding(input, prefix=embed_prefixs[id])
+            word_vecs.append(x)
+
+        semantics = []
+        for id, input in enumerate(word_vecs):
+            x = self.create_fc(input, prefix=prefixs[id])
+            semantics.append(x)
+
+        concated_vector = paddle.layer.concat(semantics)
+        prediction = paddle.layer.fc(
+            input=concated_vector,
+            size=self.class_num,
+            act=paddle.activation.Softmax())
+        cost = paddle.layer.classification_cost(input=prediction, label=label)
+        return cost, prediction, label
+
+    def _build_rank_model(self):
+        '''
+        Build a pairwise rank model, and the cost is returned.
+
+        A pairwise rank model has 3 inputs:
+          - source sentence
+          - left_target sentence
+          - right_target sentence
+          - label, 1 if left_target should be sorted in front of right_target, otherwise 0.
+        '''
+        source = paddle.layer.data(
+            name='source_input',
+            type=paddle.data_type.integer_value_sequence(self.vocab_sizes[0]))
+        left_target = paddle.layer.data(
+            name='left_target_input',
+            type=paddle.data_type.integer_value_sequence(self.vocab_sizes[1]))
+        right_target = paddle.layer.data(
+            name='right_target_input',
+            type=paddle.data_type.integer_value_sequence(self.vocab_sizes[1]))
+        label = paddle.layer.data(
+            name='label_input', type=paddle.data_type.integer_value(1))
+
+        prefixs = '_ _ _'.split(
+        ) if self.share_semantic_generator else 'source left right'.split()
+        embed_prefixs = '_ _'.split(
+        ) if self.share_embed else 'source target target'.split()
+
+        word_vecs = []
+        for id, input in enumerate([source, left_target, right_target]):
+            x = self.create_embedding(input, prefix=embed_prefixs[id])
+            word_vecs.append(x)
+
+        semantics = []
+        for id, input in enumerate(word_vecs):
+            x = self.create_fc(input, prefix=prefixs[id])
+            semantics.append(x)
+
+        # cossim score of source and left_target
+        left_score = paddle.layer.cos_sim(semantics[0], semantics[1])
+        # cossim score of source and right target
+        right_score = paddle.layer.cos_sim(semantics[0], semantics[2])
+
+        # rank cost
+        cost = paddle.layer.rank_cost(left_score, right_score, label=label)
+        # prediction = left_score - right_score
+        # but this operator is not supported currently.
+        # so AUC will not used.
+        return cost, None, None
+
+
+class RankMetrics(object):
+    '''
+    A custom metrics to calculate AUC.
+
+    Paddle's rank model do not support auc evaluator directly,
+    to make it, infer all the outputs and use python to calculate
+    the metrics.
+    '''
+
+    def __init__(self, model_parameters, left_score_layer, right_score_layer,
+                 label):
+        '''
+        @model_parameters: dict
+            model's parameters
+        @left_score_layer: paddle.layer
+            left part's score
+        @right_score_laeyr: paddle.layer
+            right part's score
+        @label: paddle.data_layer
+            label input
+        '''
+        self.inferer = paddle.inference.Inference(
+            output_layer=[left_score_layer, right_score_layer],
+            parameters=model_parameters)
+
+    def test(self, input):
+        scores = []
+        for id, rcd in enumerate(input()):
+            # output [left_score, right_score, label]
+            res = self.inferer(input=input)
+            scores.append(res)
+        print scores
diff --git a/dssm/reader.py b/dssm/reader.py
new file mode 100644
index 0000000000000000000000000000000000000000..cea53726f39ecaf292890461c5a6ed0216e53026
--- /dev/null
+++ b/dssm/reader.py
@@ -0,0 +1,83 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+from utils import UNK, TaskType, load_dic, sent2ids, logger
+
+
+class Dataset(object):
+    def __init__(self,
+                 train_path,
+                 test_path,
+                 source_dic_path,
+                 target_dic_path,
+                 task_type=TaskType.RANK):
+        self.train_path = train_path
+        self.test_path = test_path
+        self.source_dic_path = source_dic_path
+        self.target_dic_path = target_dic_path
+        self.task_type = task_type
+
+        self.source_dic = load_dic(self.source_dic_path)
+        self.target_dic = load_dic(self.target_dic_path)
+
+        self.record_reader = self._read_classification_record \
+                                if self.task_type == TaskType.CLASSFICATION \
+                                        else self._read_rank_record
+
+    def train(self):
+        logger.info("[reader] load trainset from %s" % self.train_path)
+        with open(self.train_path) as f:
+            for line_id, line in enumerate(f):
+                yield self.record_reader(line)
+
+    def test(self):
+        logger.info("[reader] load testset from %s" % self.test_path)
+        with open(self.test_path) as f:
+            for line_id, line in enumerate(f):
+                yield self.record_reader(line)
+
+    def _read_classification_record(self, line):
+        '''
+        data format:
+            <source words> [TAB] <target words> [TAB] <label>
+
+        @line: str
+            a string line which represent a record.
+        '''
+        fs = line.strip().split('\t')
+        assert len(fs) == 3, "wrong format for classification\n" + \
+            "the format shoud be " +\
+            "<source words> [TAB] <target words> [TAB] <label>'"
+        source = sent2ids(fs[0], self.source_dic)
+        target = sent2ids(fs[1], self.target_dic)
+        label = int(fs[2])
+        return (source, target, label, )
+
+    def _read_rank_record(self, line):
+        '''
+        data format:
+            <source words> [TAB] <left_target words> [TAB] <right_target words> [TAB] <label>
+        '''
+        fs = line.strip().split('\t')
+        assert len(fs) == 4, "wrong format for rank\n" + \
+            "the format should be " +\
+            "<source words> [TAB] <left_target words> [TAB] <right_target words> [TAB] <label>"
+
+        source = sent2ids(fs[0], self.source_dic)
+        left_target = sent2ids(fs[1], self.target_dic)
+        right_target = sent2ids(fs[2], self.target_dic)
+        label = int(fs[3])
+
+        return (source, left_target, right_target, label)
+
+
+if __name__ == '__main__':
+    path = './data/classification/train.txt'
+    test_path = './data/classification/test.txt'
+    source_dic = './data/vocab.txt'
+    dataset = Dataset(path, test_path, source_dic, source_dic,
+                      TaskType.CLASSFICATION)
+
+    for rcd in dataset.train():
+        print rcd
+    # for i in range(10):
+    #     print i, dataset.train().next()
diff --git a/dssm/train.py b/dssm/train.py
new file mode 100644
index 0000000000000000000000000000000000000000..e95b3d4a97f012b20042c68e0525bcd576304179
--- /dev/null
+++ b/dssm/train.py
@@ -0,0 +1,186 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+import argparse
+import gzip
+
+import paddle.v2 as paddle
+from network_conf import DSSM
+import reader
+from utils import TaskType, load_dic, logger
+
+parser = argparse.ArgumentParser(description="PaddlePaddle DSSM example")
+
+parser.add_argument(
+    '--train_data_path',
+    type=str,
+    required=False,
+    help="path of training dataset")
+parser.add_argument(
+    '--test_data_path',
+    type=str,
+    required=False,
+    help="path of testing dataset")
+parser.add_argument(
+    '--source_dic_path',
+    type=str,
+    required=False,
+    help="path of the source's word dic")
+parser.add_argument(
+    '--target_dic_path',
+    type=str,
+    required=False,
+    help="path of the target's word dic, if not set, the `source_dic_path` will be used"
+)
+parser.add_argument(
+    '--batch_size',
+    type=int,
+    default=10,
+    help="size of mini-batch (default:10)")
+parser.add_argument(
+    '--num_passes',
+    type=int,
+    default=10,
+    help="number of passes to run(default:10)")
+parser.add_argument(
+    '--task_type',
+    type=int,
+    default=TaskType.CLASSFICATION,
+    help="task type, 0 for classification, 1 for pairwise rank")
+parser.add_argument(
+    '--share_network_between_source_target',
+    type=bool,
+    default=False,
+    help="whether to share network parameters between source and target")
+parser.add_argument(
+    '--share_embed',
+    type=bool,
+    default=False,
+    help="whether to share word embedding between source and target")
+parser.add_argument(
+    '--dnn_dims',
+    type=str,
+    default='256,128,64,32',
+    help="dimentions of dnn layers, default is '256,128,64,32', which means create a 4-layer dnn, dementions of each layer is 256, 128, 64 and 32"
+)
+parser.add_argument(
+    '--num_workers', type=int, default=1, help="num worker threads, default 1")
+
+args = parser.parse_args()
+
+layer_dims = [int(i) for i in args.dnn_dims.split(',')]
+target_dic_path = args.source_dic_path if not args.target_dic_path else args.target_dic_path
+
+
+def train(train_data_path=None,
+          test_data_path=None,
+          source_dic_path=None,
+          target_dic_path=None,
+          task_type=TaskType.CLASSFICATION,
+          batch_size=10,
+          num_passes=10,
+          share_semantic_generator=False,
+          share_embed=False,
+          class_num=None,
+          num_workers=1):
+    '''
+    Train the DSSM.
+    '''
+    default_train_path = './data/rank/train.txt'
+    default_test_path = './data/rank/test.txt'
+    default_dic_path = './data/vocab.txt'
+    if task_type == TaskType.CLASSFICATION:
+        default_train_path = './data/classification/train.txt'
+        default_test_path = './data/classification/test.txt'
+
+    use_default_data = not train_data_path
+
+    if use_default_data:
+        train_data_path = default_train_path
+        test_data_path = default_test_path
+        source_dic_path = default_dic_path
+        target_dic_path = default_dic_path
+
+    dataset = reader.Dataset(
+        train_path=train_data_path,
+        test_path=test_data_path,
+        source_dic_path=source_dic_path,
+        target_dic_path=target_dic_path,
+        task_type=task_type, )
+
+    train_reader = paddle.batch(
+        paddle.reader.shuffle(dataset.train, buf_size=1000),
+        batch_size=batch_size)
+
+    test_reader = paddle.batch(
+        paddle.reader.shuffle(dataset.test, buf_size=1000),
+        batch_size=batch_size)
+
+    paddle.init(use_gpu=False, trainer_count=num_workers)
+
+    cost, prediction, label = DSSM(
+        dnn_dims=layer_dims,
+        vocab_sizes=[
+            len(load_dic(path)) for path in [source_dic_path, target_dic_path]
+        ],
+        task_type=task_type,
+        share_semantic_generator=share_semantic_generator,
+        class_num=class_num,
+        share_embed=share_embed)()
+
+    parameters = paddle.parameters.create(cost)
+
+    adam_optimizer = paddle.optimizer.Adam(
+        learning_rate=1e-3,
+        regularization=paddle.optimizer.L2Regularization(rate=1e-3),
+        model_average=paddle.optimizer.ModelAverage(average_window=0.5))
+
+    trainer = paddle.trainer.SGD(
+        cost=cost,
+        extra_layers=paddle.evaluator.auc(input=prediction, label=label)
+        if prediction else None,
+        parameters=parameters,
+        update_equation=adam_optimizer)
+
+    feeding = {}
+    if task_type == TaskType.CLASSFICATION:
+        feeding = {'source_input': 0, 'target_input': 1, 'label_input': 2}
+    else:
+        feeding = {
+            'source_input': 0,
+            'left_target_input': 1,
+            'right_target_input': 2,
+            'label_input': 3
+        }
+
+    def _event_handler(event):
+        '''
+        Define batch handler
+        '''
+        if isinstance(event, paddle.event.EndIteration):
+            if event.batch_id % 100 == 0:
+                logger.info("Pass %d, Batch %d, Cost %f, %s\n" % (
+                    event.pass_id, event.batch_id, event.cost, event.metrics))
+
+        if isinstance(event, paddle.event.EndPass):
+            if test_reader is not None:
+                if task_type == TaskType.CLASSFICATION:
+                    result = trainer.test(reader=test_reader, feeding=feeding)
+                    logger.info("Test at Pass %d, %s \n" % (event.pass_id,
+                                                            result.metrics))
+                else:
+                    result = None
+            with gzip.open("dssm_pass_%05d.tar.gz" % event.pass_id, "w") as f:
+                parameters.to_tar(f)
+
+    trainer.train(
+        reader=train_reader,
+        event_handler=_event_handler,
+        feeding=feeding,
+        num_passes=num_passes)
+
+    logger.info("Training has finished.")
+
+
+if __name__ == '__main__':
+    # train(class_num=2)
+    train(task_type=TaskType.RANK)
diff --git a/dssm/utils.py b/dssm/utils.py
new file mode 100644
index 0000000000000000000000000000000000000000..4232e182ecc4309dc302b53b6f2b6bb013e2ae19
--- /dev/null
+++ b/dssm/utils.py
@@ -0,0 +1,41 @@
+import logging
+
+UNK = 0
+
+logger = logging.getLogger("logger")
+logger.setLevel(logging.INFO)
+
+
+class TaskType:
+    '''
+    type of DSSM's task.
+    '''
+    # pairwise rank.
+    RANK = 0
+    # classification.
+    CLASSFICATION = 1
+
+
+def sent2ids(sent, vocab):
+    '''
+    transform a sentence to a list of ids.
+
+    @sent: str
+        a sentence.
+    @vocab: dict
+        a word dic
+    '''
+    return [vocab.get(w, UNK) for w in sent.split()]
+
+
+def load_dic(path):
+    '''
+    word dic format:
+      each line is a word
+    '''
+    dic = {}
+    with open(path) as f:
+        for id, line in enumerate(f):
+            w = line.strip()
+            dic[w] = id
+    return dic