diff --git a/python/paddle/fluid/dygraph/dygraph_to_static/loop_transformer.py b/python/paddle/fluid/dygraph/dygraph_to_static/loop_transformer.py
index f3f297c6a6350bf659fda9e80e1f364f7bff8f8a..2314d3c6c9500420e0f053fbf986fcd1e2dedbd5 100644
--- a/python/paddle/fluid/dygraph/dygraph_to_static/loop_transformer.py
+++ b/python/paddle/fluid/dygraph/dygraph_to_static/loop_transformer.py
@@ -80,11 +80,11 @@ class NameVisitor(gast.NodeVisitor):
         return True
 
     def get_loop_var_names(self, node):
-        assert isinstance(node, gast.While) or isinstance(
-            while_node, gast.For), "Input node is not gast loop node"
+        assert isinstance(node, (gast.While,
+                                 gast.For)), "Input node is not gast loop node"
         loop_var_names = set()
         create_var_names = set()
-        read_context = {type(gast.Load), type(gast.AugLoad)}
+        read_context = {type(gast.Load()), type(gast.AugLoad())}
 
         in_loop_vars = self.in_loop_vars[node]
         in_loop_name_strs = set(name.id for name in in_loop_vars)
@@ -114,13 +114,13 @@ class NameVisitor(gast.NodeVisitor):
 
     def visit_For(self, node):
         self.current_loop.append(node)
-        self.before_loop_vars[node] = copy.deepcopy(self.current_seen_vars)
+        self.before_loop_vars[node] = copy.copy(self.current_seen_vars)
         self.generic_visit(node)
         self.current_loop.pop()
 
     def visit_While(self, node):
         self.current_loop.append(node)
-        self.before_loop_vars[node] = copy.deepcopy(self.current_seen_vars)
+        self.before_loop_vars[node] = copy.copy(self.current_seen_vars)
         self.generic_visit(node)
         self.current_loop.pop()
 
diff --git a/python/paddle/fluid/tests/unittests/test_dygraph_to_static_loop.py b/python/paddle/fluid/tests/unittests/test_dygraph_to_static_loop.py
index 9ca551f91b88d264b02dec84f6dd1cefee27933c..c9594ff17147b74793df34cbb4ed9b7fd7e0d018 100644
--- a/python/paddle/fluid/tests/unittests/test_dygraph_to_static_loop.py
+++ b/python/paddle/fluid/tests/unittests/test_dygraph_to_static_loop.py
@@ -1,4 +1,4 @@
-#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
+#   Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@ import paddle.fluid as fluid
 import unittest
 
 from paddle.fluid.dygraph.jit import dygraph_to_static_graph
-#from paddle.fluid.dygraph.dygraph_to_static import NameVistor
+from paddle.fluid.dygraph.dygraph_to_static.loop_transformer import NameVisitor
 
 SEED = 2020
 np.random.seed(SEED)
@@ -37,8 +37,15 @@ def while_loop_dyfunc(x):
 
 class TestNameVisitor(unittest.TestCase):
     def test_loop_vars(self):
-        #TODO
-        pass
+        test_func = inspect.getsource(while_loop_dyfunc)
+        gast_root = gast.parse(test_func)
+        name_visitor = NameVisitor(gast_root)
+        for node in gast.walk(gast_root):
+            if isinstance(node, gast.While):
+                loop_var_names, create_var_names = name_visitor.get_loop_var_names(
+                    node)
+                self.assertEqual(loop_var_names, set(["i", "x"]))
+                self.assertEqual(create_var_names, set())
 
 
 class TestTransformWhile(unittest.TestCase):