diff --git a/src/main/java/io/rong/example/message/MessageExample.java b/src/main/java/io/rong/example/message/MessageExample.java
index aa8e7ce..5749343 100644
--- a/src/main/java/io/rong/example/message/MessageExample.java
+++ b/src/main/java/io/rong/example/message/MessageExample.java
@@ -349,7 +349,9 @@ public static void main(String[] args) throws Exception {
                 .setIsPersisted(0)
                 .setIsCounted(0)
                 .setIsIncludeSender(0)
-                .setContentAvailable(0);
+                .setContentAvailable(0)
+                .setExpansion(true)
+                .setExtraContent(new HashMap<String, String>());
         ResponseResult mentionResult = rongCloud.message.group.sendMention(mentionMessage);
 
         System.out.println("group mention result:  " + mentionResult.toString());
diff --git a/src/main/java/io/rong/methods/message/group/Group.java b/src/main/java/io/rong/methods/message/group/Group.java
index fb663fd..fa104ba 100644
--- a/src/main/java/io/rong/methods/message/group/Group.java
+++ b/src/main/java/io/rong/methods/message/group/Group.java
@@ -193,6 +193,12 @@ public MessageResult sendMention(MentionMessage message) throws Exception {
         if (message.getContentAvailable() != null) {
             sb.append("&contentAvailable=").append(URLEncoder.encode(message.getContentAvailable().toString(), UTF8));
         }
+        if (message.getExpansion() != null) {
+            sb.append("&expansion=").append(URLEncoder.encode(message.getExpansion().toString(), UTF8));
+            if (message.getExtraContent() != null) {
+                sb.append("&extraContent=").append(URLEncoder.encode(JSON.toJSONString(message.getExtraContent()), UTF8));
+            }
+        }
         if (message.getMsgRandom() != null){
             sb.append("&msgRandom=").append(message.getMsgRandom());
         }
diff --git a/src/main/java/io/rong/models/message/MentionMessage.java b/src/main/java/io/rong/models/message/MentionMessage.java
index 6a40704..30d3586 100644
--- a/src/main/java/io/rong/models/message/MentionMessage.java
+++ b/src/main/java/io/rong/models/message/MentionMessage.java
@@ -3,7 +3,9 @@
 import io.rong.util.GsonUtil;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 /**
  * @author rongcloud
@@ -28,6 +30,15 @@ public class MentionMessage {
     public Integer isIncludeSender;
     private Integer contentAvailable;
     private Long msgRandom;
+    /**
+     * 是否为可扩展消息，默认为 false，设为 true 时终端在收到该条消息后，可对该条消息设置扩展信息（可选）。暂不支持海外数据中心
+     */
+    public Boolean expansion;
+
+    /**
+     * 扩展消息内容，expansion 为true 的时候生效
+     */
+    public Map<String, String> extraContent;
 
     public MentionMessage() {
     }
@@ -185,4 +196,22 @@ public MentionMessage setMsgRandom(Long msgRandom) {
         this.msgRandom = msgRandom;
         return this;
     }
+
+    public Boolean getExpansion() {
+        return expansion;
+    }
+
+    public MentionMessage setExpansion(Boolean expansion) {
+        this.expansion = expansion;
+        return this;
+    }
+
+    public Map<String, String> getExtraContent() {
+        return extraContent;
+    }
+
+    public MentionMessage setExtraContent(Map<String, String> extraContent) {
+        this.extraContent = extraContent;
+        return this;
+    }
 }