diff --git a/tensorlayer/layers.py b/tensorlayer/layers.py
index 244fa7d4a..3924ae37d 100644
--- a/tensorlayer/layers.py
+++ b/tensorlayer/layers.py
@@ -2906,7 +2906,7 @@ class PoolLayer(Layer):
     """
     The :class:`PoolLayer` class is a Pooling layer, you can choose
     ``tf.nn.max_pool`` and ``tf.nn.avg_pool`` for 2D or
-    ``tf.nn.max_pool3d()`` and ``tf.nn.avg_pool3d()`` for 3D.
+    ``tf.nn.max_pool3d`` and ``tf.nn.avg_pool3d`` for 3D.
 
     Parameters
     ----------