diff --git a/fluid/neural_machine_translation/transformer/reader.py b/fluid/neural_machine_translation/transformer/reader.py
index 07553a81414343dbe232402dc1d4e429e47d46f4..7da5f35d90952f114b19982ddf951e1c2a006558 100644
--- a/fluid/neural_machine_translation/transformer/reader.py
+++ b/fluid/neural_machine_translation/transformer/reader.py
@@ -202,7 +202,6 @@ class DataReader(object):
         self._max_length = max_length
         self._field_delimiter = field_delimiter
         self._token_delimiter = token_delimiter
-        self._epoch_batches = []
         self.load_src_trg_ids(end_mark, fpattern, start_mark, tar_fname,
                               unk_mark)
         self._random = random.Random(x=seed)
@@ -248,17 +247,23 @@ class DataReader(object):
             if tar_fname is None:
                 raise Exception("If tar file provided, please set tar_fname.")
 
-            f = tarfile.open(fpaths[0], 'r')
+            f = tarfile.open(fpaths[0], "r")
             for line in f.extractfile(tar_fname):
-                yield line.split(self._field_delimiter)
+                fields = line.strip("\n").split(self._field_delimiter)
+                if (not self._only_src and len(fields) == 2) or (
+                        self._only_src and len(fields) == 1):
+                    yield fields
         else:
             for fpath in fpaths:
                 if not os.path.isfile(fpath):
                     raise IOError("Invalid file: %s" % fpath)
 
-                with open(fpath, 'r') as f:
+                with open(fpath, "r") as f:
                     for line in f:
-                        yield line.split(self._field_delimiter)
+                        fields = line.strip("\n").split(self._field_delimiter)
+                        if (not self._only_src and len(fields) == 2) or (
+                                self._only_src and len(fields) == 1):
+                            yield fields
 
     @staticmethod
     def load_dict(dict_path, reverse=False):
@@ -266,9 +271,9 @@ class DataReader(object):
         with open(dict_path, "r") as fdict:
             for idx, line in enumerate(fdict):
                 if reverse:
-                    word_dict[idx] = line.strip('\n')
+                    word_dict[idx] = line.strip("\n")
                 else:
-                    word_dict[line.strip('\n')] = idx
+                    word_dict[line.strip("\n")] = idx
         return word_dict
 
     def batch_generator(self):
@@ -285,12 +290,8 @@ class DataReader(object):
 
             if self._sort_type == SortType.POOL:
                 for i in range(0, len(infos), self._pool_size):
-                    infos[i * self._pool_size:(i + 1) *
-                          self._pool_size] = sorted(
-                              infos[i * self._pool_size:(i + 1) *
-                                    self._pool_size],
-                              key=lambda x: x.max_len,
-                              reverse=True)
+                    infos[i:i + self._pool_size] = sorted(
+                        infos[i:i + self._pool_size], key=lambda x: x.max_len)
 
         # concat batch
         batches = []