diff --git a/README.md b/README.md
index f21bc7bd9..5a40441bc 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,7 @@ OpenIsle 是一个使用 Spring Boot 和 Vue 3 构建的全栈开源社区平台
 - 集成 OpenAI 提供的 Markdown 格式化功能
 - 通过环境变量可调整密码强度、登录方式、保护码等多种配置
 - 支持图片上传，默认使用腾讯云 COS 扩展
+- 默认头像使用 DiceBear Avatars，可通过 `AVATAR_STYLE` 和 `AVATAR_SIZE` 环境变量自定义主题和大小
 - 浏览器推送通知，离开网站也能及时收到提醒
 
 ## 🌟 项目优势
diff --git a/src/main/java/com/openisle/service/AvatarGenerator.java b/src/main/java/com/openisle/service/AvatarGenerator.java
new file mode 100644
index 000000000..92895dae4
--- /dev/null
+++ b/src/main/java/com/openisle/service/AvatarGenerator.java
@@ -0,0 +1,25 @@
+package com.openisle.service;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Service;
+
+import java.net.URLEncoder;
+import java.nio.charset.StandardCharsets;
+
+@Service
+public class AvatarGenerator {
+
+    @Value("${app.avatar.base-url:https://api.dicebear.com/6.x}")
+    private String baseUrl;
+
+    @Value("${app.avatar.style:identicon}")
+    private String style;
+
+    @Value("${app.avatar.size:64}")
+    private int size;
+
+    public String generate(String seed) {
+        String encoded = URLEncoder.encode(seed, StandardCharsets.UTF_8);
+        return String.format("%s/%s/png?seed=%s&size=%d", baseUrl, style, encoded, size);
+    }
+}
diff --git a/src/main/java/com/openisle/service/GithubAuthService.java b/src/main/java/com/openisle/service/GithubAuthService.java
index 52e010c3c..739770944 100644
--- a/src/main/java/com/openisle/service/GithubAuthService.java
+++ b/src/main/java/com/openisle/service/GithubAuthService.java
@@ -10,6 +10,7 @@ import org.springframework.http.*;
 import org.springframework.stereotype.Service;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.client.HttpClientErrorException;
+import com.openisle.service.AvatarGenerator;
 
 import java.util.Collections;
 import java.util.Map;
@@ -21,6 +22,7 @@ import java.util.Optional;
 public class GithubAuthService {
     private final UserRepository userRepository;
     private final RestTemplate restTemplate = new RestTemplate();
+    private final AvatarGenerator avatarGenerator;
 
     @Value("${github.client-id:}")
     private String clientId;
@@ -117,7 +119,7 @@ public class GithubAuthService {
         if (avatar != null) {
             user.setAvatar(avatar);
         } else {
-            user.setAvatar("https://github.com/" + finalUsername + ".png");
+            user.setAvatar(avatarGenerator.generate(finalUsername));
         }
         return userRepository.save(user);
     }
diff --git a/src/main/java/com/openisle/service/GoogleAuthService.java b/src/main/java/com/openisle/service/GoogleAuthService.java
index 56b0778ec..89cee5951 100644
--- a/src/main/java/com/openisle/service/GoogleAuthService.java
+++ b/src/main/java/com/openisle/service/GoogleAuthService.java
@@ -10,6 +10,7 @@ import com.openisle.repository.UserRepository;
 import lombok.RequiredArgsConstructor;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
+import com.openisle.service.AvatarGenerator;
 
 import java.util.Collections;
 import java.util.Optional;
@@ -19,6 +20,7 @@ import java.util.Optional;
 public class GoogleAuthService {
 
     private final UserRepository userRepository;
+    private final AvatarGenerator avatarGenerator;
 
     @Value("${google.client-id:}")
     private String clientId;
@@ -70,7 +72,7 @@ public class GoogleAuthService {
         if (avatar != null) {
             user.setAvatar(avatar);
         } else {
-            user.setAvatar("https://github.com/identicons/" + username + ".png");
+            user.setAvatar(avatarGenerator.generate(username));
         }
         return userRepository.save(user);
     }
diff --git a/src/main/java/com/openisle/service/UserService.java b/src/main/java/com/openisle/service/UserService.java
index 05d2029e4..5872791c8 100644
--- a/src/main/java/com/openisle/service/UserService.java
+++ b/src/main/java/com/openisle/service/UserService.java
@@ -4,6 +4,7 @@ import com.openisle.model.User;
 import com.openisle.model.Role;
 import com.openisle.service.PasswordValidator;
 import com.openisle.service.UsernameValidator;
+import com.openisle.service.AvatarGenerator;
 import com.openisle.exception.FieldException;
 import com.openisle.repository.UserRepository;
 import lombok.RequiredArgsConstructor;
@@ -22,6 +23,7 @@ public class UserService {
     private final UsernameValidator usernameValidator;
     private final PasswordEncoder passwordEncoder = new BCryptPasswordEncoder();
     private final ImageUploader imageUploader;
+    private final AvatarGenerator avatarGenerator;
 
     public User register(String username, String email, String password, String reason, com.openisle.model.RegisterMode mode) {
         usernameValidator.validate(username);
@@ -66,7 +68,7 @@ public class UserService {
         user.setRole(Role.USER);
         user.setVerified(false);
         user.setVerificationCode(genCode());
-        user.setAvatar("https://github.com/identicons/" + username + ".png");
+        user.setAvatar(avatarGenerator.generate(username));
         user.setRegisterReason(reason);
         user.setApproved(mode == com.openisle.model.RegisterMode.DIRECT);
         return userRepository.save(user);
diff --git a/src/main/resources/application.properties b/src/main/resources/application.properties
index f1e2b2b30..01af18f2c 100644
--- a/src/main/resources/application.properties
+++ b/src/main/resources/application.properties
@@ -24,6 +24,11 @@ app.register.mode=${REGISTER_MODE:WHITELIST}
 app.upload.check-type=${UPLOAD_CHECK_TYPE:true}
 app.upload.max-size=${UPLOAD_MAX_SIZE:5242880}
 
+# Default avatar generator configuration
+app.avatar.style=${AVATAR_STYLE:identicon}
+app.avatar.size=${AVATAR_SIZE:64}
+app.avatar.base-url=${AVATAR_BASE_URL:https://api.dicebear.com/6.x}
+
 # Default list size for user posts and replies
 app.user.posts-limit=${USER_POSTS_LIMIT:10}
 app.user.replies-limit=${USER_REPLIES_LIMIT:50}