diff --git a/paddle/pybind/pybind.cc b/paddle/pybind/pybind.cc
index cbb7b1cbff91ba191b15ddbc69a3b26be319962d..cae36713509b32627e4eecf9a6153d19a2f2b9b5 100644
--- a/paddle/pybind/pybind.cc
+++ b/paddle/pybind/pybind.cc
@@ -319,17 +319,30 @@ All parameter, weight, gradient are variables in Paddle.
       .def_static("instance",
                   [] { return &GetProgramDesc(); },
                   py::return_value_policy::reference)
+      .def_static("__create_program_desc__",
+                  [] {
+                    // Only used for unit-test
+                    auto *prog_desc = new ProgramDesc;
+                    auto *block = prog_desc->mutable_blocks()->Add();
+                    block->set_idx(0);
+                    block->set_parent_idx(-1);
+                    return prog_desc;
+                  })
       .def("append_block",
            [](ProgramDesc &self, BlockDesc &parent) {
-             auto desc = self.mutable_blocks()->Add();
+             auto desc = self.add_blocks();
              desc->set_idx(self.mutable_blocks()->size() - 1);
              desc->set_parent_idx(parent.idx());
              return desc;
-           })
+           },
+           py::return_value_policy::reference)
       .def("root_block",
-           [](ProgramDesc &self) { return self.mutable_blocks()[0]; });
+           [](ProgramDesc &self) { return self.mutable_blocks()->Mutable(0); },
+           py::return_value_policy::reference)
+      .def("__str__", [](ProgramDesc &self) { return self.DebugString(); });
+
   py::class_<BlockDesc>(m, "BlockDesc", "")
-      .def("idx", [](BlockDesc &self) { return self.idx(); })
+      .def("id", [](BlockDesc &self) { return self.idx(); })
       .def("parent", [](BlockDesc &self) { return self.parent_idx(); })
       .def("append_op",
            [](BlockDesc &self) { return self.mutable_ops()->Add(); });
diff --git a/python/paddle/v2/framework/tests/test_protobuf_descs.py b/python/paddle/v2/framework/tests/test_protobuf_descs.py
index 945610ff4522311ddf36c1ef1a48550946667ed7..8e94843662639aa377616217cb15b4369f1ae4a5 100644
--- a/python/paddle/v2/framework/tests/test_protobuf_descs.py
+++ b/python/paddle/v2/framework/tests/test_protobuf_descs.py
@@ -9,8 +9,17 @@ class TestProgramDesc(unittest.TestCase):
         del program_desc
         program_desc = core.ProgramDesc.instance()
         self.assertIsNotNone(program_desc)
+        self.assertIsNotNone(program_desc.root_block())
         del program_desc
 
+    def test_append_block(self):
+        prog_desc = core.ProgramDesc.__create_program_desc__()
+        self.assertIsNotNone(prog_desc)
+        block1 = prog_desc.append_block(prog_desc.root_block())
+        block2 = prog_desc.append_block(block1)
+        self.assertEqual(block1.id(), block2.parent())
+        self.assertEqual(prog_desc.root_block().id(), block1.parent())
+
 
 if __name__ == '__main__':
     unittest.main()