diff --git a/dygraph/seq2seq/README.md b/dygraph/seq2seq/README.md
new file mode 100755
index 0000000000000000000000000000000000000000..94072c7fe5142038b348f26ba9564e6d5c8d445c
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+++ b/dygraph/seq2seq/README.md
@@ -0,0 +1,127 @@
+运行本目录下的范例模型需要安装PaddlePaddle Fluid 1.7版。如果您的 PaddlePaddle 安装版本低于此要求，请按照[安装文档](https://www.paddlepaddle.org.cn/#quick-start)中的说明更新 PaddlePaddle 安装版本。
+
+# Sequence to Sequence (Seq2Seq)
+
+以下是本范例模型的简要目录结构及说明：
+
+```
+.
+├── README.md              # 文档，本文件
+├── args.py                # 训练、预测以及模型参数配置程序
+├── reader.py              # 数据读入程序
+├── download.py            # 数据下载程序
+├── train.py               # 训练主程序
+├── infer.py               # 预测主程序
+├── run.sh                 # 默认配置的启动脚本
+├── infer.sh               # 默认配置的解码脚本
+├── attention_model.py     # 带注意力机制的翻译模型程序
+└── base_model.py          # 无注意力机制的翻译模型程序
+```
+
+## 简介
+
+Sequence to Sequence (Seq2Seq)，使用编码器-解码器（Encoder-Decoder）结构，用编码器将源序列编码成vector，再用解码器将该vector解码为目标序列。Seq2Seq 广泛应用于机器翻译，自动对话机器人，文档摘要自动生成，图片描述自动生成等任务中。
+
+本目录包含Seq2Seq的一个经典样例：机器翻译，实现了一个base model（不带attention机制），一个带attention机制的翻译模型。Seq2Seq翻译模型，模拟了人类在进行翻译类任务时的行为：先解析源语言，理解其含义，再根据该含义来写出目标语言的语句。更多关于机器翻译的具体原理和数学表达式，我们推荐参考[深度学习101](http://paddlepaddle.org/documentation/docs/zh/1.2/beginners_guide/basics/machine_translation/index.html)。
+
+**本目录旨在展示如何用Paddle Fluid 1.7的动态图接口实现一个标准的Seq2Seq模型** ，相同网络结构的静态图实现可以参照 [Seq2Seq](https://github.com/PaddlePaddle/models/tree/develop/PaddleNLP/PaddleTextGEN/seq2seq)。
+
+## 模型概览
+
+本模型中，在编码器方面，我们采用了基于LSTM的多层的RNN encoder；在解码器方面，我们使用了带注意力（Attention）机制的RNN decoder，并同时提供了一个不带注意力机制的解码器实现作为对比。在预测时我们使用柱搜索（beam search）算法来生成翻译的目标语句。以下将分别介绍用到的这些方法。
+
+## 数据介绍
+
+本教程使用[IWSLT'15 English-Vietnamese data ](https://nlp.stanford.edu/projects/nmt/)数据集中的英语到越南语的数据作为训练语料，tst2012的数据作为开发集，tst2013的数据作为测试集
+
+### 数据获取
+
+```
+python download.py
+```
+
+## 模型训练
+
+`run.sh`包含训练程序的主函数，要使用默认参数开始训练，只需要简单地执行：
+
+```
+sh run.sh
+```
+
+默认使用带有注意力机制的RNN模型，可以通过修改 --attention 为False来训练不带注意力机制的RNN模型。
+
+```
+python train.py \
+    --src_lang en --tar_lang vi \
+    --attention True \
+    --num_layers 2 \
+    --hidden_size 512 \
+    --src_vocab_size 17191 \
+    --tar_vocab_size 7709 \
+    --batch_size 128 \
+    --dropout 0.2 \
+    --init_scale  0.1 \
+    --max_grad_norm 5.0 \
+    --train_data_prefix data/en-vi/train \
+    --eval_data_prefix data/en-vi/tst2012 \
+    --test_data_prefix data/en-vi/tst2013 \
+    --vocab_prefix data/en-vi/vocab \
+    --use_gpu True \
+    --model_path ./attention_models
+```
+
+训练程序会在每个epoch训练结束之后，save一次模型。
+
+## 模型预测
+
+当模型训练完成之后， 可以利用infer.sh的脚本进行预测，默认使用beam search的方法进行预测，加载第10个epoch的模型进行预测，对test的数据集进行解码
+
+```
+sh infer.sh
+```
+
+如果想预测别的数据文件，只需要将 --infer_file参数进行修改。
+
+```
+python infer.py \
+    --attention True \
+    --src_lang en --tar_lang vi \
+    --num_layers 2 \
+    --hidden_size 512 \
+    --src_vocab_size 17191 \
+    --tar_vocab_size 7709 \
+    --batch_size 128 \
+    --dropout 0.2 \
+    --init_scale  0.1 \
+    --max_grad_norm 5.0 \
+    --vocab_prefix data/en-vi/vocab \
+    --infer_file data/en-vi/tst2013.en \
+    --reload_model attention_models/epoch_10 \
+    --infer_output_file attention_infer_output/infer_output.txt \
+    --beam_size 10 \
+    --use_gpu True
+```
+
+## 效果评价
+
+使用 [*multi-bleu.perl*](https://github.com/moses-smt/mosesdecoder.git) 工具来评价模型预测的翻译质量，使用方法如下：
+
+```sh
+mosesdecoder/scripts/generic/multi-bleu.perl tst2013.vi < infer_output.txt
+```
+
+每个模型分别训练了10次，单次取第10个epoch保存的模型进行预测，取beam_size=10。效果如下（为了便于观察，对10次结果按照升序进行了排序）：
+
+```
+> no attention
+tst2012 BLEU:
+[10.75 10.85 10.9  10.94 10.97 11.01 11.01 11.04 11.13 11.4]
+tst2013 BLEU:
+[10.71 10.71 10.74 10.76 10.91 10.94 11.02 11.16 11.21 11.44]
+
+> with attention
+tst2012 BLEU:
+[21.14 22.34 22.54 22.65 22.71 22.71 23.08 23.15 23.3  23.4]
+tst2013 BLEU:
+[23.41 24.79 25.11 25.12 25.19 25.24 25.39 25.61 25.61 25.63]
+```
diff --git a/dygraph/seq2seq/__init__.py b/dygraph/seq2seq/__init__.py
new file mode 100755
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/dygraph/seq2seq/args.py b/dygraph/seq2seq/args.py
new file mode 100755
index 0000000000000000000000000000000000000000..99f21b0800d9a2696e245fc807b393308a98e09a
--- /dev/null
+++ b/dygraph/seq2seq/args.py
@@ -0,0 +1,132 @@
+# -*- coding: utf-8 -*-
+#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import argparse
+import distutils.util
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "--train_data_prefix", type=str, help="file prefix for train data")
+    parser.add_argument(
+        "--eval_data_prefix", type=str, help="file prefix for eval data")
+    parser.add_argument(
+        "--test_data_prefix", type=str, help="file prefix for test data")
+    parser.add_argument(
+        "--vocab_prefix", type=str, help="file prefix for vocab")
+    parser.add_argument("--src_lang", type=str, help="source language suffix")
+    parser.add_argument("--tar_lang", type=str, help="target language suffix")
+
+    parser.add_argument(
+        "--attention",
+        type=eval,
+        default=False,
+        help="Whether use attention model")
+
+    parser.add_argument(
+        "--optimizer",
+        type=str,
+        default='adam',
+        help="optimizer to use, only supprt[sgd|adam]")
+
+    parser.add_argument(
+        "--learning_rate",
+        type=float,
+        default=0.001,
+        help="learning rate for optimizer")
+
+    parser.add_argument(
+        "--num_layers",
+        type=int,
+        default=1,
+        help="layers number of encoder and decoder")
+    parser.add_argument(
+        "--hidden_size",
+        type=int,
+        default=100,
+        help="hidden size of encoder and decoder")
+    parser.add_argument("--src_vocab_size", type=int, help="source vocab size")
+    parser.add_argument("--tar_vocab_size", type=int, help="target vocab size")
+
+    parser.add_argument(
+        "--batch_size", type=int, help="batch size of each step")
+
+    parser.add_argument(
+        "--max_epoch", type=int, default=12, help="max epoch for the training")
+
+    parser.add_argument(
+        "--max_len",
+        type=int,
+        default=50,
+        help="max length for source and target sentence")
+    parser.add_argument(
+        "--dropout", type=float, default=0.0, help="drop probability")
+    parser.add_argument(
+        "--init_scale",
+        type=float,
+        default=0.0,
+        help="init scale for parameter")
+    parser.add_argument(
+        "--max_grad_norm",
+        type=float,
+        default=5.0,
+        help="max grad norm for global norm clip")
+
+    parser.add_argument(
+        "--model_path",
+        type=str,
+        default='model',
+        help="model path for model to save")
+
+    parser.add_argument(
+        "--reload_model", type=str, help="reload model to inference")
+
+    parser.add_argument(
+        "--infer_file", type=str, help="file name for inference")
+    parser.add_argument(
+        "--infer_output_file",
+        type=str,
+        default='infer_output',
+        help="file name for inference output")
+    parser.add_argument(
+        "--beam_size", type=int, default=10, help="file name for inference")
+
+    parser.add_argument(
+        '--use_gpu',
+        type=eval,
+        default=False,
+        help='Whether using gpu [True|False]')
+
+    parser.add_argument(
+        "--enable_ce",
+        action='store_true',
+        help="The flag indicating whether to run the task "
+        "for continuous evaluation.")
+
+    parser.add_argument(
+        "--profile", action='store_true', help="Whether enable the profile.")
+    # NOTE: profiler args, used for benchmark
+    parser.add_argument(
+        "--profiler_path",
+        type=str,
+        default='./seq2seq.profile',
+        help="the profiler output file path. (used for benchmark)")
+    args = parser.parse_args()
+    return args
diff --git a/dygraph/seq2seq/attention_model.py b/dygraph/seq2seq/attention_model.py
new file mode 100755
index 0000000000000000000000000000000000000000..09ecfed58e70c485f3f1e962e88cd3dbda8e19f6
--- /dev/null
+++ b/dygraph/seq2seq/attention_model.py
@@ -0,0 +1,362 @@
+# -*- coding: utf-8 -*-
+#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import paddle.fluid as fluid
+import numpy as np
+from paddle.fluid import ParamAttr
+from paddle.fluid.dygraph.base import to_variable
+from paddle.fluid.dygraph.nn import Embedding, FC
+from rnn import BasicLSTMUnit
+import numpy as np
+
+INF = 1. * 1e5
+alpha = 0.6
+uniform_initializer = lambda x: fluid.initializer.UniformInitializer(low=-x, high=x)
+zero_constant = fluid.initializer.Constant(0.0)
+
+class AttentionModel(fluid.dygraph.Layer):
+    def __init__(self,
+                 hidden_size,
+                 src_vocab_size,
+                 tar_vocab_size,
+                 batch_size,
+                 num_layers=1,
+                 init_scale=0.1,
+                 dropout=None,
+                 beam_size=1,
+                 beam_start_token=1,
+                 beam_end_token=2,
+                 beam_max_step_num=100,
+                 mode='train'):
+        super(AttentionModel, self).__init__()
+        self.hidden_size = hidden_size
+        self.src_vocab_size = src_vocab_size
+        self.tar_vocab_size = tar_vocab_size
+        self.batch_size = batch_size
+        self.num_layers = num_layers
+        self.init_scale = init_scale
+        self.dropout = dropout
+        self.beam_size = beam_size
+        self.beam_start_token = beam_start_token
+        self.beam_end_token = beam_end_token
+        self.beam_max_step_num = beam_max_step_num
+        self.mode = mode
+        self.kinf = 1e9
+
+        param_attr = ParamAttr(initializer=uniform_initializer(self.init_scale))
+        bias_attr = ParamAttr(initializer=zero_constant)
+        forget_bias = 1.0
+
+        self.src_embeder = Embedding(
+            size=[self.src_vocab_size, self.hidden_size],
+            param_attr=fluid.ParamAttr(
+                name='source_embedding',
+                initializer=uniform_initializer(init_scale)))
+
+        self.tar_embeder = Embedding(
+            size=[self.tar_vocab_size, self.hidden_size],
+            is_sparse=False,
+            param_attr=fluid.ParamAttr(
+                name='target_embedding',
+                initializer=uniform_initializer(init_scale)))
+
+        self.enc_units = []
+        for i in range(num_layers):
+            self.enc_units.append(
+                self.add_sublayer("enc_units_%d" % i,
+                    BasicLSTMUnit(
+                    hidden_size=self.hidden_size, 
+                    input_size=self.hidden_size,
+                    param_attr=param_attr, 
+                    bias_attr=bias_attr, 
+                    forget_bias=forget_bias)))
+
+        self.dec_units = []
+        for i in range(num_layers):
+            if i == 0:
+                self.dec_units.append(
+                    self.add_sublayer("dec_units_%d" % i,
+                        BasicLSTMUnit(
+                        hidden_size=self.hidden_size, 
+                        input_size=self.hidden_size * 2,
+                        param_attr=param_attr, 
+                        bias_attr=bias_attr, 
+                        forget_bias=forget_bias)))
+            else:
+                self.dec_units.append(
+                    self.add_sublayer("dec_units_%d" % i,
+                    BasicLSTMUnit(
+                    hidden_size=self.hidden_size, 
+                    input_size=self.hidden_size,
+                    param_attr=param_attr, 
+                    bias_attr=bias_attr, 
+                    forget_bias=forget_bias)))
+        
+        self.fc = fluid.dygraph.nn.Linear(self.hidden_size,
+                self.tar_vocab_size, 
+                param_attr=param_attr,
+                bias_attr=False)
+        
+        self.attn_fc = fluid.dygraph.nn.Linear(self.hidden_size, 
+                self.hidden_size, 
+                param_attr=param_attr,
+                bias_attr=False)
+        
+        self.concat_fc = fluid.dygraph.nn.Linear(2 * self.hidden_size, 
+                self.hidden_size, 
+                param_attr=param_attr,
+                bias_attr=False)
+
+    def _transpose_batch_time(self, x):
+        return fluid.layers.transpose(x, [1, 0] + list(range(2, len(x.shape))))
+
+    def _merge_batch_beams(self, x):
+        return fluid.layers.reshape(x, shape=(-1,x.shape[2]))
+
+    def tile_beam_merge_with_batch(self, x):
+        x = fluid.layers.unsqueeze(x, [1])  # [batch_size, 1, ...]
+        expand_times = [1] * len(x.shape)
+        expand_times[1] = self.beam_size
+        x = fluid.layers.expand(x, expand_times)  # [batch_size, beam_size, ...]
+        x = fluid.layers.transpose(x, list(range(2, len(x.shape))) +
+                         [0, 1])  # [..., batch_size, beam_size]
+        # use 0 to copy to avoid wrong shape
+        x = fluid.layers.reshape(
+            x, shape=[0] *
+            (len(x.shape) - 2) + [-1])  # [..., batch_size * beam_size]
+        x = fluid.layers.transpose(
+            x, [len(x.shape) - 1] +
+            list(range(0, len(x.shape) - 1)))  # [batch_size * beam_size, ...]
+        return x
+
+    def _split_batch_beams(self, x):
+        return fluid.layers.reshape(x, shape=(-1, self.beam_size, x.shape[1]))
+
+    def _expand_to_beam_size(self, x):
+        x = fluid.layers.unsqueeze(x, [1])
+        expand_times = [1] * len(x.shape)
+        expand_times[1] = self.beam_size
+        x = fluid.layers.expand(x, expand_times)
+        return x
+
+    def _real_state(self, state, new_state, step_mask):
+        new_state = fluid.layers.elementwise_mul(new_state, step_mask, axis=0) - \
+                    fluid.layers.elementwise_mul(state, (step_mask - 1), axis=0)
+        return new_state
+        
+    def _gather(self, x, indices, batch_pos):
+        topk_coordinates = fluid.layers.stack([batch_pos, indices], axis=2)
+        return fluid.layers.gather_nd(x, topk_coordinates)
+
+    def attention(self, query, enc_output, mask=None):
+        query = fluid.layers.unsqueeze(query, [1])
+        memory = self.attn_fc(enc_output)
+        attn = fluid.layers.matmul(query, memory, transpose_y=True)
+
+        if mask:
+            attn = fluid.layers.transpose(attn, [1, 0, 2])
+            attn = fluid.layers.elementwise_add(attn, mask * 1000000000, -1)
+            attn = fluid.layers.transpose(attn, [1, 0, 2])
+        weight = fluid.layers.softmax(attn)
+        weight_memory = fluid.layers.matmul(weight, memory)
+
+        return weight_memory
+
+    def forward(self, inputs):
+        inputs = [fluid.dygraph.to_variable(np_inp) for np_inp in inputs]
+        src, tar, label, src_sequence_length, tar_sequence_length = inputs
+        if src.shape[0] < self.batch_size:
+            self.batch_size = src.shape[0]
+        src_emb = self.src_embeder(self._transpose_batch_time(src))
+        
+        enc_hidden = to_variable(np.zeros((self.num_layers, self.batch_size, self.hidden_size), dtype='float32'))
+        enc_cell = to_variable(np.zeros((self.num_layers, self.batch_size, self.hidden_size), dtype='float32'))
+
+        max_seq_len = src_emb.shape[0]
+        enc_len_mask = fluid.layers.sequence_mask(src_sequence_length, maxlen=max_seq_len, dtype="float32")
+        enc_padding_mask = (enc_len_mask - 1.0)
+        enc_len_mask = fluid.layers.transpose(enc_len_mask, [1, 0])
+        enc_states = [[enc_hidden, enc_cell]]
+        enc_outputs = []
+        for l in range(max_seq_len):
+            step_input = src_emb[l]
+            step_mask = enc_len_mask[l]
+            enc_hidden, enc_cell = enc_states[l]
+            new_enc_hidden, new_enc_cell = [], []
+            for i in range(self.num_layers):
+                new_hidden, new_cell = self.enc_units[i](step_input, enc_hidden[i], enc_cell[i])
+                new_enc_hidden.append(new_hidden)
+                new_enc_cell.append(new_cell)
+                if self.dropout != None and self.dropout > 0.0:
+                    step_input = fluid.layers.dropout(
+                        new_hidden,
+                        dropout_prob=self.dropout,
+                        dropout_implementation='upscale_in_train')
+                else:
+                    step_input = new_hidden
+            new_enc_hidden = [self._real_state(enc_hidden[i], new_enc_hidden[i], step_mask) for i in range(self.num_layers)]
+            new_enc_cell = [self._real_state(enc_cell[i], new_enc_cell[i], step_mask) for i in range(self.num_layers)]
+            enc_states.append([new_enc_hidden, new_enc_cell])
+            enc_outputs.append(step_input)
+        enc_outputs = fluid.layers.stack(enc_outputs)
+        enc_outputs = self._transpose_batch_time(enc_outputs)
+
+        if self.mode in ['train', 'eval']: 
+            # calculation with input_feed derives from paper: https://arxiv.org/pdf/1508.04025.pdf
+            input_feed = to_variable(np.zeros((self.batch_size, self.hidden_size), dtype='float32'))
+            
+            dec_hidden, dec_cell = enc_states[-1]
+            tar_emb = self.tar_embeder(self._transpose_batch_time(tar))
+            max_seq_len = tar_emb.shape[0]
+            dec_output = []
+
+            for step_idx in range(max_seq_len):
+                step_input = tar_emb[step_idx]
+                step_input = fluid.layers.concat([step_input, input_feed], 1)
+                new_dec_hidden, new_dec_cell = [], []
+                for i in range(self.num_layers):
+                    new_hidden, new_cell = self.dec_units[i](step_input, dec_hidden[i], dec_cell[i])
+
+                    new_dec_hidden.append(new_hidden)
+                    new_dec_cell.append(new_cell)
+                    if self.dropout != None and self.dropout > 0.0:
+                        step_input = fluid.layers.dropout(
+                            new_hidden,
+                            dropout_prob=self.dropout,
+                            dropout_implementation='upscale_in_train')
+                    else:
+                        step_input = new_hidden
+
+                dec_att = self.attention(step_input, enc_outputs, enc_padding_mask)
+                dec_att = fluid.layers.squeeze(dec_att, [1])
+                concat_att_out = fluid.layers.concat([dec_att, step_input], 1)
+                out = self.concat_fc(concat_att_out)
+                input_feed = out
+                dec_output.append(out)
+                dec_hidden, dec_cell = new_dec_hidden, new_dec_cell
+
+            dec_output = fluid.layers.stack(dec_output)
+            dec_output = self.fc(self._transpose_batch_time(dec_output))
+        
+            loss = fluid.layers.softmax_with_cross_entropy(
+            logits=dec_output, label=label, soft_label=False)
+            loss = fluid.layers.squeeze(loss, axes=[2])
+            max_tar_seq_len = fluid.layers.shape(tar)[1]
+            tar_mask = fluid.layers.sequence_mask(
+                tar_sequence_length, maxlen=max_tar_seq_len, dtype='float32')
+            loss = loss * tar_mask
+            loss = fluid.layers.reduce_mean(loss, dim=[0])
+            loss = fluid.layers.reduce_sum(loss)
+            return loss
+            
+        elif self.mode in ['beam_search']:
+            enc_outputs = self.tile_beam_merge_with_batch(enc_outputs)
+            enc_padding_mask = self.tile_beam_merge_with_batch(enc_padding_mask)
+            batch_beam_shape = (self.batch_size, self.beam_size)
+            batch_beam_shape_1 = (self.batch_size, self.beam_size, 1)
+            vocab_size_tensor = to_variable(np.full((1), self.tar_vocab_size))
+            start_token_tensor = to_variable(np.full(batch_beam_shape_1, self.beam_start_token, dtype='int64')) # remove last dim 1 in v1.7
+            end_token_tensor = to_variable(np.full(batch_beam_shape, self.beam_end_token, dtype='int64'))
+            step_input = self.tar_embeder(start_token_tensor)
+            input_feed = to_variable(np.zeros((self.batch_size, self.hidden_size), dtype='float32'))
+            input_feed = self._expand_to_beam_size(input_feed)
+            input_feed = self._merge_batch_beams(input_feed)
+            beam_finished = to_variable(np.full(batch_beam_shape, 0, dtype='float32'))
+            beam_state_log_probs = to_variable(np.array([[0.] + [-self.kinf] * (self.beam_size - 1)], dtype="float32"))
+            beam_state_log_probs = fluid.layers.expand(beam_state_log_probs, [self.batch_size, 1])
+            
+            dec_hidden, dec_cell = enc_states[-1]
+            dec_hidden = [self._expand_to_beam_size(state) for state in dec_hidden]
+            dec_cell = [self._expand_to_beam_size(state) for state in dec_cell]
+            
+            batch_pos = fluid.layers.expand(
+                fluid.layers.unsqueeze(to_variable(np.arange(0, self.batch_size, 1, dtype="int64")), [1]),
+                [1, self.beam_size])
+            predicted_ids = []
+            parent_ids = []
+
+            for step_idx in range(self.beam_max_step_num):
+                if fluid.layers.reduce_sum(1 - beam_finished).numpy()[0] == 0:
+                    break
+                step_input = self._merge_batch_beams(step_input)
+                step_input = fluid.layers.concat([step_input, input_feed], 1)
+                new_dec_hidden, new_dec_cell = [], []
+                dec_hidden = [self._merge_batch_beams(state) for state in dec_hidden]
+                dec_cell = [self._merge_batch_beams(state) for state in dec_cell]
+
+                for i in range(self.num_layers):
+                    new_hidden, new_cell = self.dec_units[i](step_input, dec_hidden[i], dec_cell[i])
+                    new_dec_hidden.append(new_hidden)
+                    new_dec_cell.append(new_cell)
+                    if self.dropout != None and self.dropout > 0.0:
+                        step_input = fluid.layers.dropout(
+                            new_hidden,
+                            dropout_prob=self.dropout,
+                            dropout_implementation='upscale_in_train')
+                    else:
+                        step_input = new_hidden
+                dec_att = self.attention(step_input, enc_outputs, enc_padding_mask)
+                dec_att = fluid.layers.squeeze(dec_att, [1])
+                concat_att_out = fluid.layers.concat([dec_att, step_input], 1)
+                out = self.concat_fc(concat_att_out)
+                input_feed = out
+                cell_outputs = self._split_batch_beams(out)
+                cell_outputs = self.fc(cell_outputs)
+                step_log_probs = fluid.layers.log(fluid.layers.softmax(cell_outputs))
+                noend_array = [-self.kinf] * self.tar_vocab_size
+                noend_array[self.beam_end_token] = 0 # [-kinf, -kinf, ..., 0, -kinf, ...]
+                noend_mask_tensor = to_variable(np.array(noend_array,dtype='float32'))
+                # set finished position to one-hot probability of <eos>
+                step_log_probs = fluid.layers.elementwise_mul(
+                        fluid.layers.expand(fluid.layers.unsqueeze(beam_finished, [2]), [1, 1, self.tar_vocab_size]),
+                    noend_mask_tensor, axis=-1) - \
+                    fluid.layers.elementwise_mul(step_log_probs, (beam_finished - 1), axis=0)
+                log_probs = fluid.layers.elementwise_add(
+                    x=step_log_probs, y=beam_state_log_probs, axis=0)
+                scores = fluid.layers.reshape(log_probs, [-1, self.beam_size * self.tar_vocab_size])
+                topk_scores, topk_indices = fluid.layers.topk(input=scores, k=self.beam_size)
+                beam_indices = fluid.layers.elementwise_floordiv(topk_indices, vocab_size_tensor) # in which beam
+                token_indices = fluid.layers.elementwise_mod(topk_indices, vocab_size_tensor) # position in beam
+                next_log_probs = self._gather(scores, topk_indices, batch_pos) # 
+
+                new_dec_hidden = [self._split_batch_beams(state) for state in new_dec_hidden]
+                new_dec_cell = [self._split_batch_beams(state) for state in new_dec_cell]
+                new_dec_hidden = [self._gather(x, beam_indices, batch_pos) for x in new_dec_hidden]
+                new_dec_cell = [self._gather(x, beam_indices, batch_pos) for x in new_dec_cell]
+                
+                next_finished = self._gather(beam_finished, beam_indices, batch_pos)              
+                next_finished = fluid.layers.cast(next_finished, "bool")
+                next_finished = fluid.layers.logical_or(next_finished, fluid.layers.equal(token_indices, end_token_tensor))
+                next_finished = fluid.layers.cast(next_finished, "float32")
+                # prepare for next step
+                dec_hidden, dec_cell = new_dec_hidden, new_dec_cell
+                beam_finished = next_finished
+                beam_state_log_probs = next_log_probs
+                step_input = self.tar_embeder(fluid.layers.unsqueeze(token_indices, 2)) # remove unsqueeze in v1.7
+                predicted_ids.append(token_indices)
+                parent_ids.append(beam_indices)
+
+            predicted_ids = fluid.layers.stack(predicted_ids)
+            parent_ids = fluid.layers.stack(parent_ids)
+            predicted_ids = fluid.layers.gather_tree(predicted_ids, parent_ids)
+            predicted_ids = self._transpose_batch_time(predicted_ids)
+            return predicted_ids
+        else:
+            print("not support mode ", self.mode)
+            raise Exception("not support mode: " + self.mode)
\ No newline at end of file
diff --git a/dygraph/seq2seq/base_model.py b/dygraph/seq2seq/base_model.py
new file mode 100755
index 0000000000000000000000000000000000000000..120d2084ee9002795911925a3f098f9009c55aa9
--- /dev/null
+++ b/dygraph/seq2seq/base_model.py
@@ -0,0 +1,285 @@
+# -*- coding: utf-8 -*-
+#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import paddle.fluid as fluid
+import numpy as np
+from paddle.fluid import ParamAttr
+from paddle.fluid.dygraph import to_variable
+from paddle.fluid.dygraph.nn import Embedding, Linear
+from rnn import BasicLSTMUnit
+import numpy as np
+
+INF = 1. * 1e5
+alpha = 0.6
+uniform_initializer = lambda x: fluid.initializer.UniformInitializer(low=-x, high=x)
+zero_constant = fluid.initializer.Constant(0.0)
+
+class BaseModel(fluid.dygraph.Layer):
+    def __init__(self,
+                 hidden_size,
+                 src_vocab_size,
+                 tar_vocab_size,
+                 batch_size,
+                 num_layers=1,
+                 init_scale=0.1,
+                 dropout=None,
+                 beam_size=1,
+                 beam_start_token=1,
+                 beam_end_token=2,
+                 beam_max_step_num=100,
+                 mode='train'):
+        super(BaseModel, self).__init__()
+        self.hidden_size = hidden_size
+        self.src_vocab_size = src_vocab_size
+        self.tar_vocab_size = tar_vocab_size
+        self.batch_size = batch_size
+        self.num_layers = num_layers
+        self.init_scale = init_scale
+        self.dropout = dropout
+        self.beam_size = beam_size
+        self.beam_start_token = beam_start_token
+        self.beam_end_token = beam_end_token
+        self.beam_max_step_num = beam_max_step_num
+        self.mode = mode
+        self.kinf = 1e9
+
+        param_attr = ParamAttr(initializer=uniform_initializer(self.init_scale))
+        bias_attr = ParamAttr(initializer=zero_constant)
+        forget_bias = 1.0
+
+        self.src_embeder = Embedding(
+            size=[self.src_vocab_size, self.hidden_size],
+            param_attr=fluid.ParamAttr(
+                initializer=uniform_initializer(init_scale)))
+
+        self.tar_embeder = Embedding(
+            size=[self.tar_vocab_size, self.hidden_size],
+            is_sparse=False,
+            param_attr=fluid.ParamAttr(
+                initializer=uniform_initializer(init_scale)))
+
+        self.enc_units = []
+        for i in range(num_layers):
+            self.enc_units.append(
+                self.add_sublayer("enc_units_%d" % i,
+                    BasicLSTMUnit(
+                    hidden_size=self.hidden_size, 
+                    input_size=self.hidden_size,
+                    param_attr=param_attr, 
+                    bias_attr=bias_attr, 
+                    forget_bias=forget_bias)))
+
+        self.dec_units = []
+        for i in range(num_layers):
+            self.dec_units.append(
+                self.add_sublayer("dec_units_%d" % i,
+                    BasicLSTMUnit(
+                    hidden_size=self.hidden_size, 
+                    input_size=self.hidden_size,
+                    param_attr=param_attr, 
+                    bias_attr=bias_attr, 
+                    forget_bias=forget_bias)))
+        
+        self.fc = fluid.dygraph.nn.Linear(self.hidden_size,
+                self.tar_vocab_size,
+                param_attr=param_attr,
+                bias_attr=False)
+
+    def _transpose_batch_time(self, x):
+        return fluid.layers.transpose(x, [1, 0] + list(range(2, len(x.shape))))
+
+    def _merge_batch_beams(self, x):
+        return fluid.layers.reshape(x, shape=(-1,x.shape[2]))
+
+    def _split_batch_beams(self, x):
+        return fluid.layers.reshape(x, shape=(-1, self.beam_size, x.shape[1]))
+
+    def _expand_to_beam_size(self, x):
+        x = fluid.layers.unsqueeze(x, [1])
+        expand_times = [1] * len(x.shape)
+        expand_times[1] = self.beam_size
+        x = fluid.layers.expand(x, expand_times)
+        return x
+
+    def _real_state(self, state, new_state, step_mask):
+        new_state = fluid.layers.elementwise_mul(new_state, step_mask, axis=0) - \
+                    fluid.layers.elementwise_mul(state, (step_mask - 1), axis=0)
+        return new_state
+
+    def _gather(self, x, indices, batch_pos):
+        topk_coordinates = fluid.layers.stack([batch_pos, indices], axis=2)
+        return fluid.layers.gather_nd(x, topk_coordinates)
+
+    def forward(self, inputs):
+        #inputs[0] = np.expand_dims(inputs[0], axis=-1)
+        #inputs[1] = np.expand_dims(inputs[1], axis=-1)
+        inputs = [fluid.dygraph.to_variable(np_inp) for np_inp in inputs]
+        src, tar, label, src_sequence_length, tar_sequence_length = inputs
+        if src.shape[0] < self.batch_size:
+            self.batch_size = src.shape[0]
+        src_emb = self.src_embeder(self._transpose_batch_time(src))
+
+        enc_hidden = to_variable(np.zeros((self.num_layers, self.batch_size, self.hidden_size), dtype='float32'))
+        enc_cell = to_variable(np.zeros((self.num_layers, self.batch_size, self.hidden_size), dtype='float32'))
+
+        max_seq_len = src_emb.shape[0]
+        enc_len_mask = fluid.layers.sequence_mask(src_sequence_length, maxlen=max_seq_len, dtype="float32")
+        enc_len_mask = fluid.layers.transpose(enc_len_mask, [1, 0])
+        enc_states = [[enc_hidden, enc_cell]]
+        for l in range(max_seq_len):
+            step_input = src_emb[l]
+            step_mask = enc_len_mask[l]
+            enc_hidden, enc_cell = enc_states[l]
+            new_enc_hidden, new_enc_cell = [], []
+            for i in range(self.num_layers):
+                new_hidden, new_cell = self.enc_units[i](step_input, enc_hidden[i], enc_cell[i])
+                new_enc_hidden.append(new_hidden)
+                new_enc_cell.append(new_cell)
+                if self.dropout != None and self.dropout > 0.0:
+                    step_input = fluid.layers.dropout(
+                        new_hidden,
+                        dropout_prob=self.dropout,
+                        dropout_implementation='upscale_in_train')
+                else:
+                    step_input = new_hidden
+            new_enc_hidden = [self._real_state(enc_hidden[i], new_enc_hidden[i], step_mask) for i in range(self.num_layers)]
+            new_enc_cell = [self._real_state(enc_cell[i], new_enc_cell[i], step_mask) for i in range(self.num_layers)]
+            enc_states.append([new_enc_hidden, new_enc_cell])
+        
+        if self.mode in ['train', 'eval']:
+            dec_hidden, dec_cell = enc_states[-1]
+            tar_emb = self.tar_embeder(self._transpose_batch_time(tar))
+            max_seq_len = tar_emb.shape[0]
+            dec_output = []
+
+            for step_idx in range(max_seq_len):
+                step_input = tar_emb[step_idx]
+                new_dec_hidden, new_dec_cell = [], []
+                for i in range(self.num_layers):
+                    new_hidden, new_cell = self.dec_units[i](step_input, dec_hidden[i], dec_cell[i])
+                    new_dec_hidden.append(new_hidden)
+                    new_dec_cell.append(new_cell)
+                    if self.dropout != None and self.dropout > 0.0:
+                        step_input = fluid.layers.dropout(
+                            new_hidden,
+                            dropout_prob=self.dropout,
+                            dropout_implementation='upscale_in_train')
+                    else:
+                        step_input = new_hidden
+                dec_output.append(step_input)
+                dec_hidden, dec_cell = new_dec_hidden, new_dec_cell
+
+            dec_output = fluid.layers.stack(dec_output)
+            dec_output = self.fc(self._transpose_batch_time(dec_output))
+        
+            loss = fluid.layers.softmax_with_cross_entropy(
+            logits=dec_output, label=label, soft_label=False)
+            loss = fluid.layers.squeeze(loss, axes=[2])
+            max_tar_seq_len = fluid.layers.shape(tar)[1]
+            tar_mask = fluid.layers.sequence_mask(
+                tar_sequence_length, maxlen=max_tar_seq_len, dtype='float32')
+            loss = loss * tar_mask
+            loss = fluid.layers.reduce_mean(loss, dim=[0])
+            loss = fluid.layers.reduce_sum(loss)
+            return loss
+        elif self.mode in ['beam_search']:
+            batch_beam_shape = (self.batch_size, self.beam_size)
+            #batch_beam_shape_1 = (self.batch_size, self.beam_size, 1)
+            vocab_size_tensor = to_variable(np.full((1), self.tar_vocab_size))
+            start_token_tensor = to_variable(np.full(batch_beam_shape, self.beam_start_token, dtype='int64')) # remove last dim 1 in v1.7
+            end_token_tensor = to_variable(np.full(batch_beam_shape, self.beam_end_token, dtype='int64'))
+            step_input = self.tar_embeder(start_token_tensor)
+            beam_finished = to_variable(np.full(batch_beam_shape, 0, dtype='float32'))
+            beam_state_log_probs = to_variable(np.array([[0.] + [-self.kinf] * (self.beam_size - 1)], dtype="float32"))
+            beam_state_log_probs = fluid.layers.expand(beam_state_log_probs, [self.batch_size, 1])
+            
+            dec_hidden, dec_cell = enc_states[-1]
+            dec_hidden = [self._expand_to_beam_size(state) for state in dec_hidden]
+            dec_cell = [self._expand_to_beam_size(state) for state in dec_cell]
+            
+            batch_pos = fluid.layers.expand(
+                fluid.layers.unsqueeze(to_variable(np.arange(0, self.batch_size, 1, dtype="int64")), [1]),
+                [1, self.beam_size])
+            predicted_ids = []
+            parent_ids = []
+
+            for step_idx in range(self.beam_max_step_num):
+                if fluid.layers.reduce_sum(1 - beam_finished).numpy()[0] == 0:
+                    break
+                step_input = self._merge_batch_beams(step_input)
+                new_dec_hidden, new_dec_cell = [], []
+                dec_hidden = [self._merge_batch_beams(state) for state in dec_hidden]
+                dec_cell = [self._merge_batch_beams(state) for state in dec_cell]
+
+                for i in range(self.num_layers):
+                    new_hidden, new_cell = self.dec_units[i](step_input, dec_hidden[i], dec_cell[i])
+                    new_dec_hidden.append(new_hidden)
+                    new_dec_cell.append(new_cell)
+                    if self.dropout != None and self.dropout > 0.0:
+                        step_input = fluid.layers.dropout(
+                            new_hidden,
+                            dropout_prob=self.dropout,
+                            dropout_implementation='upscale_in_train')
+                    else:
+                        step_input = new_hidden
+                cell_outputs = self._split_batch_beams(step_input)
+                cell_outputs = self.fc(cell_outputs) 
+                # Beam_search_step:
+                step_log_probs = fluid.layers.log(fluid.layers.softmax(cell_outputs))
+                noend_array = [-self.kinf] * self.tar_vocab_size
+                noend_array[self.beam_end_token] = 0 # [-kinf, -kinf, ..., 0, -kinf, ...]
+                noend_mask_tensor = to_variable(np.array(noend_array,dtype='float32'))
+                # set finished position to one-hot probability of <eos>
+                step_log_probs = fluid.layers.elementwise_mul(
+                        fluid.layers.expand(fluid.layers.unsqueeze(beam_finished, [2]), [1, 1, self.tar_vocab_size]),
+                    noend_mask_tensor, axis=-1) - \
+                    fluid.layers.elementwise_mul(step_log_probs, (beam_finished - 1), axis=0)
+                log_probs = fluid.layers.elementwise_add(
+                    x=step_log_probs, y=beam_state_log_probs, axis=0)
+                scores = fluid.layers.reshape(log_probs, [-1, self.beam_size * self.tar_vocab_size])
+                topk_scores, topk_indices = fluid.layers.topk(input=scores, k=self.beam_size)
+                beam_indices = fluid.layers.elementwise_floordiv(topk_indices, vocab_size_tensor) # in which beam
+                token_indices = fluid.layers.elementwise_mod(topk_indices, vocab_size_tensor) # position in beam
+                next_log_probs = self._gather(scores, topk_indices, batch_pos) # 
+
+                new_dec_hidden = [self._split_batch_beams(state) for state in new_dec_hidden]
+                new_dec_cell = [self._split_batch_beams(state) for state in new_dec_cell]
+                new_dec_hidden = [self._gather(x, beam_indices, batch_pos) for x in new_dec_hidden]
+                new_dec_cell = [self._gather(x, beam_indices, batch_pos) for x in new_dec_cell]
+                
+                next_finished = self._gather(beam_finished, beam_indices, batch_pos)              
+                next_finished = fluid.layers.cast(next_finished, "bool")
+                next_finished = fluid.layers.logical_or(next_finished, fluid.layers.equal(token_indices, end_token_tensor))
+                next_finished = fluid.layers.cast(next_finished, "float32")
+                # prepare for next step
+                dec_hidden, dec_cell = new_dec_hidden, new_dec_cell
+                beam_finished = next_finished
+                beam_state_log_probs = next_log_probs
+                step_input = self.tar_embeder(fluid.layers.unsqueeze(token_indices, 2)) # remove unsqueeze in v1.7
+                predicted_ids.append(token_indices)
+                parent_ids.append(beam_indices)
+
+            predicted_ids = fluid.layers.stack(predicted_ids)
+            parent_ids = fluid.layers.stack(parent_ids)
+            predicted_ids = fluid.layers.gather_tree(predicted_ids, parent_ids)
+            predicted_ids = self._transpose_batch_time(predicted_ids)
+            return predicted_ids
+        else:
+            print("not support mode ", self.mode)
+            raise Exception("not support mode: " + self.mode)
\ No newline at end of file
diff --git a/dygraph/seq2seq/download.py b/dygraph/seq2seq/download.py
new file mode 100755
index 0000000000000000000000000000000000000000..4dd1466d25bf16d7b4fc9bc3819fff8fe12f7adf
--- /dev/null
+++ b/dygraph/seq2seq/download.py
@@ -0,0 +1,55 @@
+# -*- coding: utf-8 -*-
+#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the 'License');
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an 'AS IS' BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+'''
+Script for downloading training data.
+'''
+import os
+import urllib
+import sys
+
+if sys.version_info >= (3, 0):
+    import urllib.request
+import zipfile
+
+URLLIB = urllib
+if sys.version_info >= (3, 0):
+    URLLIB = urllib.request
+
+remote_path = 'https://nlp.stanford.edu/projects/nmt/data/iwslt15.en-vi'
+base_path = 'data'
+tar_path = os.path.join(base_path, 'en-vi')
+filenames = [
+    'train.en', 'train.vi', 'tst2012.en', 'tst2012.vi', 'tst2013.en',
+    'tst2013.vi', 'vocab.en', 'vocab.vi'
+]
+
+
+def main(arguments):
+    print("Downloading data......")
+
+    if not os.path.exists(tar_path):
+        if not os.path.exists(base_path):
+            os.mkdir(base_path)
+        os.mkdir(tar_path)
+
+    for filename in filenames:
+        url = remote_path + '/' + filename
+        tar_file = os.path.join(tar_path, filename)
+        URLLIB.urlretrieve(url, tar_file)
+    print("Downloaded sucess......")
+
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv[1:]))
diff --git a/dygraph/seq2seq/infer.py b/dygraph/seq2seq/infer.py
new file mode 100755
index 0000000000000000000000000000000000000000..4a531661fd3280f96707ba480cb1806fc051b818
--- /dev/null
+++ b/dygraph/seq2seq/infer.py
@@ -0,0 +1,170 @@
+# -*- coding: utf-8 -*-
+#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import numpy as np
+import time
+import os
+import random
+import logging
+import math
+import io
+import paddle
+import paddle.fluid as fluid
+
+import reader
+
+import sys
+line_tok = '\n'
+space_tok = ' '
+if sys.version[0] == '2':
+    reload(sys)
+    sys.setdefaultencoding("utf-8")
+    line_tok = u'\n'
+    space_tok = u' '
+
+logging.basicConfig(format='%(asctime)s - %(levelname)s - %(message)s')
+logger = logging.getLogger("fluid")
+logger.setLevel(logging.INFO)
+
+from args import *
+import logging
+import pickle
+
+from attention_model import AttentionModel
+from base_model import BaseModel
+
+
+def infer():
+    args = parse_args()
+
+    num_layers = args.num_layers
+    src_vocab_size = args.src_vocab_size
+    tar_vocab_size = args.tar_vocab_size
+    batch_size = args.batch_size
+    dropout = args.dropout
+    init_scale = args.init_scale
+    max_grad_norm = args.max_grad_norm
+    hidden_size = args.hidden_size
+    # inference process
+
+    print("src", src_vocab_size)
+    place = fluid.CUDAPlace(0) if args.use_gpu else fluid.CPUPlace()
+    with fluid.dygraph.guard(place):
+        # dropout type using upscale_in_train, dropout can be remove in inferecen
+        # So we can set dropout to 0
+        if args.attention:
+            model = AttentionModel(
+                "attention_model",
+                hidden_size,
+                src_vocab_size,
+                tar_vocab_size,
+                batch_size,
+                beam_size = args.beam_size,
+                num_layers=num_layers,
+                init_scale=init_scale,
+                dropout=0.0,
+                mode='beam_search')
+        else:
+            model = BaseModel(
+                "base_model",
+                hidden_size,
+                src_vocab_size,
+                tar_vocab_size,
+                batch_size,
+                beam_size = args.beam_size,
+                num_layers=num_layers,
+                init_scale=init_scale,
+                dropout=0.0,
+                mode='beam_search')
+
+        source_vocab_file = args.vocab_prefix + "." + args.src_lang
+        infer_file = args.infer_file
+
+        infer_data = reader.raw_mono_data(source_vocab_file, infer_file)
+
+        def prepare_input(batch, epoch_id=0):
+                src_ids, src_mask, tar_ids, tar_mask = batch
+                res = {}
+                src_ids = src_ids.reshape((src_ids.shape[0], src_ids.shape[1]))
+                in_tar = tar_ids[:, :-1]
+                label_tar = tar_ids[:, 1:]
+
+                in_tar = in_tar.reshape((in_tar.shape[0], in_tar.shape[1]))
+                label_tar = label_tar.reshape(
+                    (label_tar.shape[0], label_tar.shape[1], 1))
+                inputs = [src_ids, in_tar, label_tar, src_mask, tar_mask]
+                return inputs, np.sum(tar_mask)
+
+        dir_name = args.reload_model
+        print("dir name", dir_name)
+        state_dict, _ = fluid.dygraph.load_dygraph(dir_name)
+        model.set_dict(state_dict)
+        model.eval()
+
+        train_data_iter = reader.get_data_iter(infer_data, batch_size, mode='infer')
+
+        tar_id2vocab = []
+        tar_vocab_file = args.vocab_prefix + "." + args.tar_lang
+        with io.open(tar_vocab_file, "r", encoding='utf-8') as f:
+            for line in f.readlines():
+                tar_id2vocab.append(line.strip())
+
+        infer_output_file = args.infer_output_file
+        infer_output_dir = infer_output_file.split('/')[0]
+        if not os.path.exists(infer_output_dir):
+            os.mkdir(infer_output_dir)
+
+        with io.open(infer_output_file, 'w', encoding='utf-8') as out_file:
+
+            for batch_id, batch in enumerate(train_data_iter):
+                input_data_feed, word_num = prepare_input(batch, epoch_id=0)
+                outputs = model(input_data_feed)
+         
+                for i in range(outputs.shape[0]):
+                    ins = fluid.Variable.numpy(outputs[i])
+                    res = [tar_id2vocab[e] for e in ins[:, 0].reshape(-1)]
+                    new_res = []
+                    for ele in res:
+                        if ele == "</s>":
+                            break
+                        new_res.append(ele)
+
+                    out_file.write(space_tok.join(new_res))
+                    out_file.write(line_tok)
+
+
+def check_version():
+    """
+    Log error and exit when the installed version of paddlepaddle is
+    not satisfied.
+    """
+    err = "PaddlePaddle version 1.6 or higher is required, " \
+          "or a suitable develop version is satisfied as well. \n" \
+          "Please make sure the version is good with your code." \
+
+    try:
+        fluid.require_version('1.6.0')
+    except Exception as e:
+        logger.error(err)
+        sys.exit(1)
+
+
+if __name__ == '__main__':
+    check_version()
+    infer()
diff --git a/dygraph/seq2seq/infer.sh b/dygraph/seq2seq/infer.sh
new file mode 100755
index 0000000000000000000000000000000000000000..5c79b9ee838dc28bd1eec261eb5301ebadc208d0
--- /dev/null
+++ b/dygraph/seq2seq/infer.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+export CUDA_VISIBLE_DEVICES=7
+
+python infer.py \
+    --attention True \
+    --src_lang en --tar_lang vi \
+    --num_layers 2 \
+    --hidden_size 512 \
+    --src_vocab_size 17191 \
+    --tar_vocab_size 7709 \
+    --batch_size 1 \
+    --dropout 0.2 \
+    --init_scale  0.1 \
+    --max_grad_norm 5.0 \
+    --vocab_prefix data/en-vi/vocab \
+    --infer_file data/en-vi/tst2013.en \
+    --reload_model attention_models/epoch_10 \
+    --infer_output_file attention_infer_output/infer_output.txt \
+    --beam_size 10 \
+    --use_gpu True
+
+
diff --git a/dygraph/seq2seq/reader.py b/dygraph/seq2seq/reader.py
new file mode 100755
index 0000000000000000000000000000000000000000..4f27560722a839c6bc51b3302fe1cc6b36064b65
--- /dev/null
+++ b/dygraph/seq2seq/reader.py
@@ -0,0 +1,220 @@
+# -*- coding: utf-8 -*-
+#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Utilities for parsing PTB text files."""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import collections
+import os
+import io
+import sys
+import numpy as np
+
+Py3 = sys.version_info[0] == 3
+
+UNK_ID = 0
+
+
+def _read_words(filename):
+    data = []
+    with io.open(filename, "r", encoding='utf-8') as f:
+        if Py3:
+            return f.read().replace("\n", "<eos>").split()
+        else:
+            return f.read().decode("utf-8").replace(u"\n", u"<eos>").split()
+
+
+def read_all_line(filenam):
+    data = []
+    with io.open(filename, "r", encoding='utf-8') as f:
+        for line in f.readlines():
+            data.append(line.strip())
+
+
+def _build_vocab(filename):
+
+    vocab_dict = {}
+    ids = 0
+    with io.open(filename, "r", encoding='utf-8') as f:
+        for line in f.readlines():
+            vocab_dict[line.strip()] = ids
+            ids += 1
+
+    print("vocab word num", ids)
+
+    return vocab_dict
+
+
+def _para_file_to_ids(src_file, tar_file, src_vocab, tar_vocab):
+
+    src_data = []
+    with io.open(src_file, "r", encoding='utf-8') as f_src:
+        for line in f_src.readlines():
+            arra = line.strip().split()
+            ids = [src_vocab[w] if w in src_vocab else UNK_ID for w in arra]
+            ids = ids
+
+            src_data.append(ids)
+
+    tar_data = []
+    with io.open(tar_file, "r", encoding='utf-8') as f_tar:
+        for line in f_tar.readlines():
+            arra = line.strip().split()
+            ids = [tar_vocab[w] if w in tar_vocab else UNK_ID for w in arra]
+
+            ids = [1] + ids + [2]
+
+            tar_data.append(ids)
+
+    return src_data, tar_data
+
+
+def filter_len(src, tar, max_sequence_len=50):
+    new_src = []
+    new_tar = []
+
+    for id1, id2 in zip(src, tar):
+        if len(id1) > max_sequence_len:
+            id1 = id1[:max_sequence_len]
+        if len(id2) > max_sequence_len + 2:
+            id2 = id2[:max_sequence_len + 2]
+
+        new_src.append(id1)
+        new_tar.append(id2)
+
+    return new_src, new_tar
+
+
+def raw_data(src_lang,
+             tar_lang,
+             vocab_prefix,
+             train_prefix,
+             eval_prefix,
+             test_prefix,
+             max_sequence_len=50):
+
+    src_vocab_file = vocab_prefix + "." + src_lang
+    tar_vocab_file = vocab_prefix + "." + tar_lang
+
+    src_train_file = train_prefix + "." + src_lang
+    tar_train_file = train_prefix + "." + tar_lang
+
+    src_eval_file = eval_prefix + "." + src_lang
+    tar_eval_file = eval_prefix + "." + tar_lang
+
+    src_test_file = test_prefix + "." + src_lang
+    tar_test_file = test_prefix + "." + tar_lang
+
+    src_vocab = _build_vocab(src_vocab_file)
+    tar_vocab = _build_vocab(tar_vocab_file)
+
+    train_src, train_tar = _para_file_to_ids( src_train_file, tar_train_file, \
+                                              src_vocab, tar_vocab )
+    train_src, train_tar = filter_len(
+        train_src, train_tar, max_sequence_len=max_sequence_len)
+    eval_src, eval_tar = _para_file_to_ids( src_eval_file, tar_eval_file, \
+                                              src_vocab, tar_vocab )
+
+    test_src, test_tar = _para_file_to_ids( src_test_file, tar_test_file, \
+                                              src_vocab, tar_vocab )
+
+    return ( train_src, train_tar), (eval_src, eval_tar), (test_src, test_tar),\
+            (src_vocab, tar_vocab)
+
+
+def raw_mono_data(vocab_file, file_path):
+
+    src_vocab = _build_vocab(vocab_file)
+
+    test_src, test_tar = _para_file_to_ids( file_path, file_path, \
+                                              src_vocab, src_vocab )
+
+    return (test_src, test_tar)
+
+
+def get_data_iter(raw_data,
+                  batch_size,
+                  mode='train',
+                  enable_ce=False,
+                  cache_num=20):
+
+    src_data, tar_data = raw_data
+
+    data_len = len(src_data)
+
+    index = np.arange(data_len)
+    if mode == "train" and not enable_ce:
+        np.random.shuffle(index)
+
+    def to_pad_np(data, source=False):
+        max_len = 0
+        bs = min(batch_size, len(data))
+        for ele in data:
+            if len(ele) > max_len:
+                max_len = len(ele)
+
+        ids = np.ones((bs, max_len), dtype='int64') * 2
+        mask = np.zeros((bs), dtype='int32')
+
+        for i, ele in enumerate(data):
+            ids[i, :len(ele)] = ele
+            if not source:
+                mask[i] = len(ele) - 1
+            else:
+                mask[i] = len(ele)
+
+        return ids, mask
+
+    b_src = []
+
+    if mode != "train":
+        cache_num = 1
+    for j in range(data_len):
+        if len(b_src) == batch_size * cache_num:
+            # build batch size
+
+            # sort
+            if mode == 'infer':
+                new_cache = b_src
+            else:
+                new_cache = sorted(b_src, key=lambda k: len(k[0]))
+            
+
+            for i in range(cache_num):
+                batch_data = new_cache[i * batch_size:(i + 1) * batch_size]
+                src_cache = [w[0] for w in batch_data]
+                tar_cache = [w[1] for w in batch_data]
+                src_ids, src_mask = to_pad_np(src_cache, source=True)
+                tar_ids, tar_mask = to_pad_np(tar_cache)
+                yield (src_ids, src_mask, tar_ids, tar_mask)
+
+            b_src = []
+
+        b_src.append((src_data[index[j]], tar_data[index[j]]))
+    if len(b_src) == batch_size * cache_num or mode == 'infer':
+        if mode == 'infer':
+            new_cache = b_src
+        else:
+            new_cache = sorted(b_src, key=lambda k: len(k[0]))
+
+        for i in range(cache_num):
+            batch_end = min(len(new_cache), (i + 1) * batch_size)
+            batch_data = new_cache[i * batch_size: batch_end]
+            src_cache = [w[0] for w in batch_data]
+            tar_cache = [w[1] for w in batch_data]
+            src_ids, src_mask = to_pad_np(src_cache, source=True)
+            tar_ids, tar_mask = to_pad_np(tar_cache)
+            yield (src_ids, src_mask, tar_ids, tar_mask)
diff --git a/dygraph/seq2seq/rnn.py b/dygraph/seq2seq/rnn.py
new file mode 100644
index 0000000000000000000000000000000000000000..9d841530ebd865e3c6e21911ef8b04da498ded15
--- /dev/null
+++ b/dygraph/seq2seq/rnn.py
@@ -0,0 +1,94 @@
+from paddle.fluid import layers
+from paddle.fluid.dygraph import Layer
+
+class BasicLSTMUnit(Layer):
+    """
+    ****
+    BasicLSTMUnit class, Using basic operator to build LSTM
+    The algorithm can be described as the code below.
+        .. math::
+           i_t &= \sigma(W_{ix}x_{t} + W_{ih}h_{t-1} + b_i)
+           f_t &= \sigma(W_{fx}x_{t} + W_{fh}h_{t-1} + b_f + forget_bias )
+           o_t &= \sigma(W_{ox}x_{t} + W_{oh}h_{t-1} + b_o)
+           \\tilde{c_t} &= tanh(W_{cx}x_t + W_{ch}h_{t-1} + b_c)
+           c_t &= f_t \odot c_{t-1} + i_t \odot \\tilde{c_t}
+           h_t &= o_t \odot tanh(c_t)
+        - $W$ terms denote weight matrices (e.g. $W_{ix}$ is the matrix
+          of weights from the input gate to the input)
+        - The b terms denote bias vectors ($bx_i$ and $bh_i$ are the input gate bias vector).
+        - sigmoid is the logistic sigmoid function.
+        - $i, f, o$ and $c$ are the input gate, forget gate, output gate,
+          and cell activation vectors, respectively, all of which have the same size as
+          the cell output activation vector $h$.
+        - The :math:`\odot` is the element-wise product of the vectors.
+        - :math:`tanh` is the activation functions.
+        - :math:`\\tilde{c_t}` is also called candidate hidden state,
+          which is computed based on the current input and the previous hidden state.
+    Args:
+        name_scope(string) : The name scope used to identify parameter and bias name
+        hidden_size (integer): The hidden size used in the Unit.
+        param_attr(ParamAttr|None): The parameter attribute for the learnable
+            weight matrix. Note:
+            If it is set to None or one attribute of ParamAttr, lstm_unit will
+            create ParamAttr as param_attr. If the Initializer of the param_attr
+            is not set, the parameter is initialized with Xavier. Default: None.
+        bias_attr (ParamAttr|None): The parameter attribute for the bias
+            of LSTM unit.
+            If it is set to None or one attribute of ParamAttr, lstm_unit will 
+            create ParamAttr as bias_attr. If the Initializer of the bias_attr
+            is not set, the bias is initialized as zero. Default: None.
+        gate_activation (function|None): The activation function for gates (actGate).
+                                  Default: 'fluid.layers.sigmoid'
+        activation (function|None): The activation function for cells (actNode).
+                             Default: 'fluid.layers.tanh'
+        forget_bias(float|1.0): forget bias used when computing forget gate
+        dtype(string): data type used in this unit
+    """
+
+    def __init__(self,
+                 hidden_size,
+                 input_size,
+                 param_attr=None,
+                 bias_attr=None,
+                 gate_activation=None,
+                 activation=None,
+                 forget_bias=1.0,
+                 dtype='float32'):
+        super(BasicLSTMUnit, self).__init__(dtype)
+
+        self._hiden_size = hidden_size
+        self._param_attr = param_attr
+        self._bias_attr = bias_attr
+        self._gate_activation = gate_activation or layers.sigmoid
+        self._activation = activation or layers.tanh
+        self._forget_bias = layers.fill_constant(
+            [1], dtype=dtype, value=forget_bias)
+        self._forget_bias.stop_gradient = False
+        self._dtype = dtype
+        self._input_size = input_size
+
+        self._weight = self.create_parameter(
+            attr=self._param_attr,
+            shape=[self._input_size + self._hiden_size, 4 * self._hiden_size],
+            dtype=self._dtype)
+
+        self._bias = self.create_parameter(
+            attr=self._bias_attr,
+            shape=[4 * self._hiden_size],
+            dtype=self._dtype,
+            is_bias=True)
+
+    def forward(self, input, pre_hidden, pre_cell):
+        concat_input_hidden = layers.concat([input, pre_hidden], 1)
+        gate_input = layers.matmul(x=concat_input_hidden, y=self._weight)
+
+        gate_input = layers.elementwise_add(gate_input, self._bias)
+        i, j, f, o = layers.split(gate_input, num_or_sections=4, dim=-1)
+        new_cell = layers.elementwise_add(
+            layers.elementwise_mul(
+                pre_cell,
+                layers.sigmoid(layers.elementwise_add(f, self._forget_bias))),
+            layers.elementwise_mul(layers.sigmoid(i), layers.tanh(j)))
+        new_hidden = layers.tanh(new_cell) * layers.sigmoid(o)
+
+        return new_hidden, new_cell
\ No newline at end of file
diff --git a/dygraph/seq2seq/run.sh b/dygraph/seq2seq/run.sh
new file mode 100755
index 0000000000000000000000000000000000000000..25bc78a3c7f3303324c0f5fb9aac14b467918a16
--- /dev/null
+++ b/dygraph/seq2seq/run.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+export CUDA_VISIBLE_DEVICES=0
+
+python train.py \
+        --src_lang en --tar_lang vi \
+        --attention True \
+        --num_layers 2 \
+        --hidden_size 512 \
+        --src_vocab_size 17191 \
+        --tar_vocab_size 7709 \
+        --batch_size 128 \
+        --dropout 0.2 \
+        --init_scale  0.1 \
+        --max_grad_norm 5.0 \
+        --train_data_prefix data/en-vi/train \
+        --eval_data_prefix data/en-vi/tst2012 \
+        --test_data_prefix data/en-vi/tst2013 \
+        --vocab_prefix data/en-vi/vocab \
+        --use_gpu True \
+        --model_path attention_models
diff --git a/dygraph/seq2seq/train.py b/dygraph/seq2seq/train.py
new file mode 100755
index 0000000000000000000000000000000000000000..a25dccc8b316c1cd61672bd47730379f49802ea2
--- /dev/null
+++ b/dygraph/seq2seq/train.py
@@ -0,0 +1,220 @@
+# -*- coding: utf-8 -*-
+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import numpy as np
+import time
+import os
+import logging
+import random
+import math
+import contextlib
+
+import paddle
+import paddle.fluid as fluid
+from paddle.fluid.dygraph_grad_clip import GradClipByGlobalNorm
+
+import reader
+
+import sys
+if sys.version[0] == '2':
+    reload(sys)
+    sys.setdefaultencoding("utf-8")
+
+from args import *
+from base_model import BaseModel
+from attention_model import AttentionModel
+import logging
+import pickle
+
+
+def main():
+    args = parse_args()
+    print(args)
+    num_layers = args.num_layers
+    src_vocab_size = args.src_vocab_size
+    tar_vocab_size = args.tar_vocab_size
+    batch_size = args.batch_size
+    dropout = args.dropout
+    init_scale = args.init_scale
+    max_grad_norm = args.max_grad_norm
+    hidden_size = args.hidden_size
+
+    place = fluid.CUDAPlace(0) if args.use_gpu else fluid.CPUPlace()
+    with fluid.dygraph.guard(place):
+        args.enable_ce = True
+        if args.enable_ce:
+            fluid.default_startup_program().random_seed = 102
+            fluid.default_main_program().random_seed = 102
+            np.random.seed(102)
+            random.seed(102)
+
+        # Training process
+
+        if args.attention:
+            model = AttentionModel(
+                hidden_size,
+                src_vocab_size,
+                tar_vocab_size,
+                batch_size,
+                num_layers=num_layers,
+                init_scale=init_scale,
+                dropout=dropout)
+        else:
+            model = BaseModel(
+                hidden_size,
+                src_vocab_size,
+                tar_vocab_size,
+                batch_size,
+                num_layers=num_layers,
+                init_scale=init_scale,
+                dropout=dropout)
+        gloabl_norm_clip = GradClipByGlobalNorm(max_grad_norm)
+        lr = args.learning_rate
+        opt_type = args.optimizer
+        if opt_type == "sgd":
+            optimizer = fluid.optimizer.SGD(lr, parameter_list=model.parameters())
+        elif opt_type == "adam":
+            optimizer = fluid.optimizer.Adam(lr, parameter_list=model.parameters())
+        else:
+            print("only support [sgd|adam]")
+            raise Exception("opt type not support")
+
+        train_data_prefix = args.train_data_prefix
+        eval_data_prefix = args.eval_data_prefix
+        test_data_prefix = args.test_data_prefix
+        vocab_prefix = args.vocab_prefix
+        src_lang = args.src_lang
+        tar_lang = args.tar_lang
+        print("begin to load data")
+        raw_data = reader.raw_data(src_lang, tar_lang, vocab_prefix,
+                                train_data_prefix, eval_data_prefix,
+                                test_data_prefix, args.max_len)
+        print("finished load data")
+        train_data, valid_data, test_data, _ = raw_data
+
+        def prepare_input(batch, epoch_id=0):
+            src_ids, src_mask, tar_ids, tar_mask = batch
+            res = {}
+            src_ids = src_ids.reshape((src_ids.shape[0], src_ids.shape[1]))
+            in_tar = tar_ids[:, :-1]
+            label_tar = tar_ids[:, 1:]
+
+            in_tar = in_tar.reshape((in_tar.shape[0], in_tar.shape[1]))
+            label_tar = label_tar.reshape(
+                (label_tar.shape[0], label_tar.shape[1], 1))
+            inputs = [src_ids, in_tar, label_tar, src_mask, tar_mask]
+            return inputs, np.sum(tar_mask)
+
+        # get train epoch size
+        def eval(data, epoch_id=0):
+            model.eval()
+            eval_data_iter = reader.get_data_iter(data, batch_size, mode='eval')
+            total_loss = 0.0
+            word_count = 0.0
+            for batch_id, batch in enumerate(eval_data_iter):
+                input_data_feed, word_num = prepare_input(
+                    batch, epoch_id)
+                loss = model(input_data_feed)
+
+                total_loss += loss * batch_size
+                word_count += word_num
+            ppl = np.exp(total_loss.numpy() / word_count)
+            model.train()
+            return ppl
+
+        max_epoch = args.max_epoch
+        for epoch_id in range(max_epoch):
+            model.train()
+            start_time = time.time()
+            if args.enable_ce:
+                train_data_iter = reader.get_data_iter(
+                    train_data, batch_size, enable_ce=True)
+            else:
+                train_data_iter = reader.get_data_iter(train_data, batch_size)
+
+            total_loss = 0
+            word_count = 0.0
+            batch_times = []
+            for batch_id, batch in enumerate(train_data_iter):
+                batch_start_time = time.time()
+                input_data_feed, word_num = prepare_input(
+                    batch, epoch_id=epoch_id)
+                word_count += word_num
+                loss = model(input_data_feed)
+                # print(loss.numpy()[0])
+                loss.backward()
+                optimizer.minimize(loss, grad_clip = gloabl_norm_clip)
+                model.clear_gradients()
+                total_loss += loss * batch_size
+                batch_end_time = time.time()
+                batch_time = batch_end_time - batch_start_time
+                batch_times.append(batch_time)
+
+                if batch_id > 0 and batch_id % 100 == 0:
+                    print("-- Epoch:[%d]; Batch:[%d]; Time: %.5f s; ppl: %.5f" %
+                        (epoch_id, batch_id, batch_time,
+                        np.exp(total_loss.numpy() / word_count)))
+                    total_loss = 0.0
+                    word_count = 0.0
+
+            end_time = time.time()
+            epoch_time = end_time - start_time
+            print(
+                "\nTrain epoch:[%d]; Epoch Time: %.5f; avg_time: %.5f s/step\n"
+                % (epoch_id, epoch_time, sum(batch_times) / len(batch_times)))
+
+            
+            dir_name = os.path.join(args.model_path,
+                                    "epoch_" + str(epoch_id))
+            print("begin to save", dir_name)
+            paddle.fluid.save_dygraph(model.state_dict(), dir_name)
+            print("save finished")
+            dev_ppl = eval(valid_data)
+            print("dev ppl", dev_ppl)
+            test_ppl = eval(test_data)
+            print("test ppl", test_ppl)
+
+
+def get_cards():
+    num = 0
+    cards = os.environ.get('CUDA_VISIBLE_DEVICES', '')
+    if cards != '':
+        num = len(cards.split(","))
+    return num
+
+
+def check_version():
+    """
+    Log error and exit when the installed version of paddlepaddle is
+    not satisfied.
+    """
+    err = "PaddlePaddle version 1.6 or higher is required, " \
+          "or a suitable develop version is satisfied as well. \n" \
+          "Please make sure the version is good with your code." \
+
+    try:
+        fluid.require_version('1.6.0')
+    except Exception as e:
+        logger.error(err)
+        sys.exit(1)
+
+
+if __name__ == '__main__':
+    check_version()
+    main()