diff --git a/doc/fluid/api_cn/initializer_cn/BilinearInitializer_cn.rst b/doc/fluid/api_cn/initializer_cn/BilinearInitializer_cn.rst
index ce2ac4598f95535ef7e6c91e82fccdcb35dab2c2..4e3031e4f0a8d4d4ac5879f450289fa3d600168d 100644
--- a/doc/fluid/api_cn/initializer_cn/BilinearInitializer_cn.rst
+++ b/doc/fluid/api_cn/initializer_cn/BilinearInitializer_cn.rst
@@ -16,6 +16,7 @@ BilinearInitializer
 .. code-block:: python
 
     import paddle.fluid as fluid
+    import math
     factor = 2
     C = 2
     H = W = 32