diff --git a/python/paddle/v2/optimizer.py b/python/paddle/v2/optimizer.py
index b6ee51cfe899fd0652fd3bf702ddcb440c3c7566..a3997994069e5b0625dc88bb7313db4160a60c6c 100644
--- a/python/paddle/v2/optimizer.py
+++ b/python/paddle/v2/optimizer.py
@@ -35,6 +35,7 @@ class Optimizer(object):
         For each optimizer(SGD, Adam), GradientMachine should enable different
         buffers.
         """
+        import py_paddle.swig_paddle as swig_api
         tmp = swig_api.ParameterOptimizer.create(self.__opt_conf__)
         assert isinstance(tmp, swig_api.ParameterOptimizer)
         return tmp.getParameterTypes()