diff --git a/python/paddle/fluid/layers/rnn.py b/python/paddle/fluid/layers/rnn.py
index 7f815e1c74dfa6bcca867cbe797dca5755e608ed..c0ad3e3bea7d71bbd923d274c84a4ef522adeeac 100644
--- a/python/paddle/fluid/layers/rnn.py
+++ b/python/paddle/fluid/layers/rnn.py
@@ -880,6 +880,9 @@ class BeamSearchDecoder(Decoder):
     :code:`BeamSearchDecoder.tile_beam_merge_with_batch` . The most common case
     for this is the encoder output in attention mechanism.
 
+    Returns:
+        BeamSearchDecoder: An instance of decoder which can be used in \
+            `paddle.nn.dynamic_decode` to implement decoding. 
 
     Examples: