diff --git a/client/src/test/java/com/alibaba/nacos/client/naming/event/InstancesChangeEventTest.java b/client/src/test/java/com/alibaba/nacos/client/naming/event/InstancesChangeEventTest.java
new file mode 100644
index 000000000..c4c6d78cb
--- /dev/null
+++ b/client/src/test/java/com/alibaba/nacos/client/naming/event/InstancesChangeEventTest.java
@@ -0,0 +1,44 @@
+/*
+ *   Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ *   Licensed under the Apache License, Version 2.0 (the "License");
+ *   you may not use this file except in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   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.
+ */
+
+package com.alibaba.nacos.client.naming.event;
+
+import com.alibaba.nacos.api.naming.pojo.Instance;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class InstancesChangeEventTest {
+    
+    @Test
+    public void testGetServiceName() {
+        String serviceName = "a";
+        String groupName = "b";
+        String clusters = "c";
+        List<Instance> hosts = new ArrayList<>();
+        Instance ins = new Instance();
+        hosts.add(ins);
+        InstancesChangeEvent event = new InstancesChangeEvent(serviceName, groupName, clusters, hosts);
+        Assert.assertEquals(serviceName, event.getServiceName());
+        Assert.assertEquals(clusters, event.getClusters());
+        Assert.assertEquals(groupName, event.getGroupName());
+        List<Instance> hosts1 = event.getHosts();
+        Assert.assertEquals(hosts.size(), hosts1.size());
+        Assert.assertEquals(hosts.get(0), hosts1.get(0));
+    }
+}
\ No newline at end of file
diff --git a/client/src/test/java/com/alibaba/nacos/client/naming/event/InstancesChangeNotifierTest.java b/client/src/test/java/com/alibaba/nacos/client/naming/event/InstancesChangeNotifierTest.java
new file mode 100644
index 000000000..bf7319b34
--- /dev/null
+++ b/client/src/test/java/com/alibaba/nacos/client/naming/event/InstancesChangeNotifierTest.java
@@ -0,0 +1,101 @@
+/*
+ *   Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ *   Licensed under the Apache License, Version 2.0 (the "License");
+ *   you may not use this file except in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   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.
+ */
+
+package com.alibaba.nacos.client.naming.event;
+
+import com.alibaba.nacos.api.naming.listener.EventListener;
+import com.alibaba.nacos.api.naming.pojo.ServiceInfo;
+import org.junit.Assert;
+import org.junit.Test;
+import org.mockito.Mockito;
+
+import java.util.List;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+
+public class InstancesChangeNotifierTest {
+    
+    @Test
+    public void testRegisterListener() {
+        String group = "a";
+        String name = "b";
+        String clusters = "c";
+        InstancesChangeNotifier instancesChangeNotifier = new InstancesChangeNotifier();
+        EventListener listener = Mockito.mock(EventListener.class);
+        instancesChangeNotifier.registerListener(group, name, clusters, listener);
+        List<ServiceInfo> subscribeServices = instancesChangeNotifier.getSubscribeServices();
+        Assert.assertEquals(1, subscribeServices.size());
+        Assert.assertEquals(group, subscribeServices.get(0).getGroupName());
+        Assert.assertEquals(name, subscribeServices.get(0).getName());
+        Assert.assertEquals(clusters, subscribeServices.get(0).getClusters());
+        
+    }
+    
+    @Test
+    public void testDeregisterListener() {
+        String group = "a";
+        String name = "b";
+        String clusters = "c";
+        InstancesChangeNotifier instancesChangeNotifier = new InstancesChangeNotifier();
+        EventListener listener = Mockito.mock(EventListener.class);
+        instancesChangeNotifier.registerListener(group, name, clusters, listener);
+        List<ServiceInfo> subscribeServices = instancesChangeNotifier.getSubscribeServices();
+        Assert.assertEquals(1, subscribeServices.size());
+        
+        instancesChangeNotifier.deregisterListener(group, name, clusters, listener);
+        
+        List<ServiceInfo> subscribeServices2 = instancesChangeNotifier.getSubscribeServices();
+        Assert.assertEquals(1, subscribeServices2.size());
+    }
+    
+    @Test
+    public void testIsSubscribed() {
+        String group = "a";
+        String name = "b";
+        String clusters = "c";
+        InstancesChangeNotifier instancesChangeNotifier = new InstancesChangeNotifier();
+        EventListener listener = Mockito.mock(EventListener.class);
+        Assert.assertFalse(instancesChangeNotifier.isSubscribed(group, name, clusters));
+        
+        instancesChangeNotifier.registerListener(group, name, clusters, listener);
+        Assert.assertTrue(instancesChangeNotifier.isSubscribed(group, name, clusters));
+    }
+    
+    @Test
+    public void testOnEvent() {
+        String group = "a";
+        String name = "b";
+        String clusters = "c";
+        InstancesChangeNotifier instancesChangeNotifier = new InstancesChangeNotifier();
+        EventListener listener = Mockito.mock(EventListener.class);
+        
+        instancesChangeNotifier.registerListener(group, name, clusters, listener);
+        InstancesChangeEvent event1 = Mockito.mock(InstancesChangeEvent.class);
+        Mockito.when(event1.getClusters()).thenReturn(clusters);
+        Mockito.when(event1.getGroupName()).thenReturn(group);
+        Mockito.when(event1.getServiceName()).thenReturn(name);
+        
+        instancesChangeNotifier.onEvent(event1);
+        Mockito.verify(listener, times(1)).onEvent(any());
+    }
+    
+    @Test
+    public void testSubscribeType() {
+        InstancesChangeNotifier instancesChangeNotifier = new InstancesChangeNotifier();
+        Assert.assertEquals(InstancesChangeEvent.class, instancesChangeNotifier.subscribeType());
+    }
+}
\ No newline at end of file