diff --git a/python/paddle/v2/framework/tests/mnist.py b/python/paddle/v2/framework/tests/mnist.py
index 0c27ce3e355b6accac96ca57bb08564742ffc318..d9941023fe69fcd6e924766ef88702b4818abeee 100644
--- a/python/paddle/v2/framework/tests/mnist.py
+++ b/python/paddle/v2/framework/tests/mnist.py
@@ -7,6 +7,8 @@ BATCH_SIZE = 100
 
 scope = core.Scope()
 place = core.CPUPlace()
+# if you want to test GPU training, you can use gpu place
+# place = core.GPUPlace(0)
 dev_ctx = core.DeviceContext.create(place)
 
 init_net = core.Net.create()