diff --git a/python/paddle/v2/framework/optimizer.py b/python/paddle/v2/framework/optimizer.py
index 51d435668ce2ab6b5f369fbfb715c072f4a7a0b7..ba2713e34dbfeca6990c49d0388e0886426b921a 100644
--- a/python/paddle/v2/framework/optimizer.py
+++ b/python/paddle/v2/framework/optimizer.py
@@ -279,7 +279,7 @@ class AdagradOptimizer(Optimizer):
     """
     _moment_acc_str = "moment"
 
-    def __init__(self, learning_rate, epsilon):
+    def __init__(self, learning_rate, epsilon=1.0e-6):
         assert learning_rate is not None
         assert epsilon is not None
         super(AdagradOptimizer, self).__init__()