diff --git a/python/paddle/fluid/layers/nn.py b/python/paddle/fluid/layers/nn.py
index 7bb6bd7d0e135b9466b67e9b0a87a24b2d1afce9..71d8bd8677bb0e74c67bdfde7eea55ac1d2f5fc2 100644
--- a/python/paddle/fluid/layers/nn.py
+++ b/python/paddle/fluid/layers/nn.py
@@ -1762,7 +1762,8 @@ def softmax(input, use_cudnn=False, name=None):
     Args:
         input (Variable): The input variable.
         use_cudnn (bool): Use cudnn kernel or not, it is valid only when the cudnn \
-            library is installed.
+            library is installed. To improve numerical stablity, set use_cudnn to \
+            False by default. Default: False
         name (str|None): A name for this layer(optional). If set None, the layer
             will be named automatically. Default: None.