diff --git a/python/src/main.cpp b/python/src/main.cpp
index fc1222b70..b920bf2b9 100644
--- a/python/src/main.cpp
+++ b/python/src/main.cpp
@@ -883,8 +883,8 @@ PYBIND11_MODULE(ncnn, m)
 
     .def("clear", &Net::clear)
     .def("create_extractor", &Net::create_extractor)
-    .def("blobs", &Net::blobs)
-    .def("layers", &Net::layers);
+    .def("blobs", &Net::blobs, py::return_value_policy::reference_internal)
+    .def("layers", &Net::layers, py::return_value_policy::reference_internal);
 
     py::enum_<ncnn::BorderType>(m, "BorderType")
     .value("BORDER_CONSTANT", ncnn::BorderType::BORDER_CONSTANT)
diff --git a/python/tests/custom_layer.param b/python/tests/custom_layer.param
new file mode 100644
index 000000000..16a1a613f
--- /dev/null
+++ b/python/tests/custom_layer.param
@@ -0,0 +1,4 @@
+7767517
+2 2
+Input            data                             0 1 data
+CustomLayer      cl_fwd                           1 1 data output
diff --git a/python/tests/test.py b/python/tests/test.py
deleted file mode 100644
index 3f3423213..000000000
--- a/python/tests/test.py
+++ /dev/null
@@ -1,33 +0,0 @@
-# Tencent is pleased to support the open source community by making ncnn available.
-#
-# Copyright (C) 2020 THL A29 Limited, a Tencent company. All rights reserved.
-#
-# Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
-# in compliance with the License. You may obtain a copy of the License at
-#
-# https://opensource.org/licenses/BSD-3-Clause
-#
-# Unless required by applicable law or agreed to in writing, software distributed
-# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
-# CONDITIONS OF ANY KIND, either express or implied. See the License for the
-# specific language governing permissions and limitations under the License.
-
-import time
-import ncnn
-
-dr = ncnn.DataReaderFromEmpty()
-
-net = ncnn.Net()
-net.load_param("test.param")
-net.load_model(dr)
-
-in_mat = ncnn.Mat((227, 227, 3))
-
-start = time.time()
-
-ex = net.create_extractor()
-ex.input("data", in_mat)
-ret, out_mat = ex.extract("output")
-
-end = time.time()
-print("timespan = ", end - start)
diff --git a/python/tests/test_net.py b/python/tests/test_net.py
new file mode 100644
index 000000000..e312902c1
--- /dev/null
+++ b/python/tests/test_net.py
@@ -0,0 +1,89 @@
+# Tencent is pleased to support the open source community by making ncnn available.
+#
+# Copyright (C) 2021 THL A29 Limited, a Tencent company. All rights reserved.
+#
+# Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
+# in compliance with the License. You may obtain a copy of the License at
+#
+# https://opensource.org/licenses/BSD-3-Clause
+#
+# Unless required by applicable law or agreed to in writing, software distributed
+# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+# CONDITIONS OF ANY KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations under the License.
+
+import numpy as np
+import pytest
+
+import ncnn
+
+
+def test_net():
+    dr = ncnn.DataReaderFromEmpty()
+
+    net = ncnn.Net()
+    ret = net.load_param("tests/test.param")
+    net.load_model(dr)
+    assert ret == 0 and len(net.blobs()) == 3 and len(net.layers()) == 3
+
+    in_mat = ncnn.Mat((227, 227, 3))
+
+    ex = net.create_extractor()
+    ex.input("data", in_mat)
+    ret, out_mat = ex.extract("output")
+
+    assert ret == 0 and out_mat.dims == 1 and out_mat.w == 1
+
+    net.clear()
+    assert len(net.blobs()) == 0 and len(net.layers()) == 0
+
+
+def test_custom_layer():
+    class CustomLayer(ncnn.Layer):
+        customLayers = []
+
+        def __init__(self):
+            ncnn.Layer.__init__(self)
+            self.one_blob_only = True
+
+            self.customLayers.append(self)
+
+        def forward(self, bottom_blob, top_blob, opt):
+            x = np.array(bottom_blob)
+            x += 1
+
+            top_blob.clone_from(ncnn.Mat(x), opt.blob_allocator)
+            if top_blob.empty():
+                return -100
+
+            return 0
+
+    def CustomLayer_layer_creator():
+        return CustomLayer()
+
+    def CustomLayer_layer_destroyer(layer):
+        for i in range(len(CustomLayer.customLayers)):
+            if CustomLayer.customLayers[i] == layer:
+                del CustomLayer.customLayers[i]
+                break
+
+    dr = ncnn.DataReaderFromEmpty()
+
+    net = ncnn.Net()
+    net.register_custom_layer(
+        "CustomLayer", CustomLayer_layer_creator, CustomLayer_layer_destroyer
+    )
+    ret = net.load_param("tests/custom_layer.param")
+    net.load_model(dr)
+    assert ret == 0 and len(net.blobs()) == 2 and len(net.layers()) == 2
+
+    in_mat = ncnn.Mat(1)
+    in_mat.fill(1.0)
+
+    ex = net.create_extractor()
+    ex.input("data", in_mat)
+    ret, out_mat = ex.extract("output")
+    assert ret == 0 and out_mat.dims == 1 and out_mat.w == 1 and out_mat[0] == 2.0
+
+    net.clear()
+    assert len(net.blobs()) == 0 and len(net.layers()) == 0