diff --git a/api/chat.py b/api/chat.py
index eb71a1f..470be83 100644
--- a/api/chat.py
+++ b/api/chat.py
@@ -434,7 +434,7 @@ class RoomInfoHandler(api.base.ApiHandler):
 
 class AvatarHandler(api.base.ApiHandler):
     async def get(self):
-        # uid基本是0了，现在这个接口唯一的作用是算用户名MD5，其实可以放到前端
+        # uid基本是0了，现在都是前端计算默认头像URL，这个接口留着只是为了兼容旧版
         uid = int(self.get_query_argument('uid'))
         username = self.get_query_argument('username', '')
         avatar_url = await services.avatar.get_avatar_url_or_none(uid)
diff --git a/frontend/package.json b/frontend/package.json
index 555bda3..712f262 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -10,6 +10,7 @@
   "dependencies": {
     "axios": "^1.4.0",
     "core-js": "^3.8.3",
+    "crypto-js": "^4.2.0",
     "downloadjs": "^1.4.7",
     "element-ui": "^2.15.13",
     "lodash": "^4.17.21",
diff --git a/frontend/src/api/chat/index.js b/frontend/src/api/chat/index.js
index 195b59e..db2090d 100644
--- a/frontend/src/api/chat/index.js
+++ b/frontend/src/api/chat/index.js
@@ -1,4 +1,5 @@
 import axios from 'axios'
+import MD5 from 'crypto-js/md5'
 
 export function getDefaultMsgHandler() {
   let dummyFunc = () => {}
@@ -27,6 +28,10 @@ export function processAvatarUrl(avatarUrl) {
 }
 
 export async function getAvatarUrl(uid, username) {
+  if (uid === 0) {
+    return getDefaultAvatarUrl(uid, username)
+  }
+
   let res
   try {
     res = (await axios.get('/api/avatar_url', { params: {
@@ -34,11 +39,24 @@ export async function getAvatarUrl(uid, username) {
       username: username
     } })).data
   } catch {
-    return DEFAULT_AVATAR_URL
+    return getDefaultAvatarUrl(uid, username)
   }
   return res.avatarUrl
 }
 
+export function getDefaultAvatarUrl(uid, username) {
+  let strToHash
+  if (uid !== 0) {
+    strToHash = uid.toString()
+  } else if (username !== '') {
+    strToHash = username
+  } else {
+    return DEFAULT_AVATAR_URL
+  }
+  let idHash = MD5(strToHash).toString()
+  return `//cravatar.cn/avatar/${idHash}?s=256&d=robohash&f=y`
+}
+
 export async function getTextEmoticons() {
   let res
   try {