diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index d1dd9b90708a..b9f84d592a70 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -192,6 +192,7 @@ List of Contributors
 * [Rahul Padmanabhan](https://github.com/rahul3)
 * [Yuxi Hu](https://github.com/yuxihu)
 * [Harsh Patel](https://github.com/harshp8l)
+* [Xiao Wang](https://github.com/BeyonderXX)
 
 Label Bot
 ---------
diff --git a/python/mxnet/gluon/rnn/rnn_cell.py b/python/mxnet/gluon/rnn/rnn_cell.py
index 98e96fc6da17..6ef3604eb973 100644
--- a/python/mxnet/gluon/rnn/rnn_cell.py
+++ b/python/mxnet/gluon/rnn/rnn_cell.py
@@ -102,6 +102,23 @@ def _mask_sequence_variable_length(F, data, length, valid_length, time_axis, mer
                                    squeeze_axis=True))
     return outputs
 
+def _reverse_sequences(sequences, unroll_step, valid_length=None):
+    if isinstance(sequences[0], symbol.Symbol):
+        F = symbol
+    else:
+        F = ndarray
+
+    if valid_length is None:
+        reversed_sequences = list(reversed(sequences))
+    else:
+        reversed_sequences = F.SequenceReverse(F.stack(*sequences, axis=0),
+                                               sequence_length=valid_length,
+                                               use_sequence_length=True)
+        reversed_sequences = F.split(reversed_sequences, axis=0, num_outputs=unroll_step, squeeze_axis=True)
+
+    return reversed_sequences
+
+
 class RecurrentCell(Block):
     """Abstract base class for RNN cells
 
@@ -1035,14 +1052,7 @@ def unroll(self, length, inputs, begin_state=None, layout='NTC', merge_outputs=N
         self.reset()
 
         inputs, axis, F, batch_size = _format_sequence(length, inputs, layout, False)
-        if valid_length is None:
-            reversed_inputs = list(reversed(inputs))
-        else:
-            reversed_inputs = F.SequenceReverse(F.stack(*inputs, axis=0),
-                                                sequence_length=valid_length,
-                                                use_sequence_length=True)
-            reversed_inputs = _as_list(F.split(reversed_inputs, axis=0, num_outputs=length,
-                                               squeeze_axis=True))
+        reversed_inputs = list(_reverse_sequences(inputs, length, valid_length))
         begin_state = _get_begin_state(self, F, begin_state, inputs, batch_size)
 
         states = begin_state
@@ -1056,15 +1066,8 @@ def unroll(self, length, inputs, begin_state=None, layout='NTC', merge_outputs=N
                                             begin_state=states[len(l_cell.state_info(batch_size)):],
                                             layout=layout, merge_outputs=False,
                                             valid_length=valid_length)
-        if valid_length is None:
-            reversed_r_outputs = list(reversed(r_outputs))
-        else:
-            reversed_r_outputs = F.SequenceReverse(F.stack(*r_outputs, axis=0),
-                                                   sequence_length=valid_length,
-                                                   use_sequence_length=True,
-                                                   axis=0)
-            reversed_r_outputs = _as_list(F.split(reversed_r_outputs, axis=0, num_outputs=length,
-                                                  squeeze_axis=True))
+        reversed_r_outputs = _reverse_sequences(r_outputs, length, valid_length)
+
         if merge_outputs is None:
             merge_outputs = isinstance(l_outputs, tensor_types)
             l_outputs, _, _, _ = _format_sequence(None, l_outputs, layout, merge_outputs)
diff --git a/tests/python/unittest/test_gluon_rnn.py b/tests/python/unittest/test_gluon_rnn.py
index eee3adda2c65..edc43d21b36b 100644
--- a/tests/python/unittest/test_gluon_rnn.py
+++ b/tests/python/unittest/test_gluon_rnn.py
@@ -600,6 +600,34 @@ def test_layer_fill_shape():
     assert layer.l0_i2h_weight.shape[1] == 7, layer.l0_i2h_weight.shape[1]
 
 
+def test_bidirectional_unroll_valid_length():
+    # Test BidirectionalCell.
+    # In 1.3.1 version, after hybridize( ), BidirectionalCell would failed when pass valid_length to unroll( ).
+    class BiLSTM(gluon.nn.HybridBlock):
+        def __init__(self, rnn_size, time_step, **kwargs):
+            super(BiLSTM, self).__init__(**kwargs)
+            self.time_step = time_step
+            with self.name_scope():
+                self.bi_lstm = gluon.rnn.BidirectionalCell(
+                    gluon.rnn.LSTMCell(rnn_size, prefix='rnn_l0_'),
+                    gluon.rnn.LSTMCell(rnn_size, prefix='rnn_r0_'),
+                    output_prefix='lstm_bi_')
+
+        def hybrid_forward(self, F, inputs, valid_len):
+            outputs, states = self.bi_lstm.unroll(self.time_step, inputs, valid_length=valid_len,
+                                                  layout='NTC', merge_outputs=True)
+            return outputs, states
+
+    rnn_size, time_step = 100, 3
+    net = BiLSTM(rnn_size, time_step)
+    net.initialize()
+    net.hybridize()
+    inputs_data = mx.nd.random.uniform(shape=(10, 3, 50))
+    valid_len = mx.nd.array([1]*10)
+    outputs, _ = net(inputs_data, valid_len)
+    assert outputs.shape == (10, 3, 200)
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule()