diff --git a/.env.example b/.env.example
index 957f980..5b574b2 100644
--- a/.env.example
+++ b/.env.example
@@ -69,6 +69,18 @@ SENTRY_DSN=
 LOG_LEVEL=INFO
 # 是否输出 JSON 格式日志。
 LOG_JSON=false
+# 是否在后端启动时自动创建默认管理员。
+DEFAULT_ADMIN_ENABLED=true
+# 默认管理员手机号，可用于登录管理端。
+DEFAULT_ADMIN_PHONE=13900000001
+# 默认管理员邮箱，也可用于登录管理端。
+DEFAULT_ADMIN_EMAIL=admin@ciyuan.local
+# 默认管理员密码，生产环境必须修改。
+DEFAULT_ADMIN_PASSWORD=admin123456
+# 默认管理员昵称。
+DEFAULT_ADMIN_NICKNAME=系统管理员
+# 启动时是否把已有默认管理员密码同步为 DEFAULT_ADMIN_PASSWORD。
+DEFAULT_ADMIN_SYNC_PASSWORD=true
 
 # 管理端前端构建配置
 # 管理端构建阶段 Node 基础镜像。
diff --git a/docker-compose.yml b/docker-compose.yml
index 800661a..6fab80a 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -86,6 +86,12 @@ services:
       SENTRY_DSN: "${SENTRY_DSN}"
       LOG_LEVEL: "${LOG_LEVEL}"
       LOG_JSON: "${LOG_JSON}"
+      DEFAULT_ADMIN_ENABLED: "${DEFAULT_ADMIN_ENABLED}"
+      DEFAULT_ADMIN_PHONE: "${DEFAULT_ADMIN_PHONE}"
+      DEFAULT_ADMIN_EMAIL: "${DEFAULT_ADMIN_EMAIL}"
+      DEFAULT_ADMIN_PASSWORD: "${DEFAULT_ADMIN_PASSWORD}"
+      DEFAULT_ADMIN_NICKNAME: "${DEFAULT_ADMIN_NICKNAME}"
+      DEFAULT_ADMIN_SYNC_PASSWORD: "${DEFAULT_ADMIN_SYNC_PASSWORD}"
     expose:
       - "${SERVER_INTERNAL_PORT}"
     volumes:
diff --git a/server/README.md b/server/README.md
index 44ace6a..0a74ae2 100644
--- a/server/README.md
+++ b/server/README.md
@@ -1,6 +1,8 @@
 # 后端默认管理员账号
 
-- 管理后台登录账号（手机号）：`13900000001`
-- 管理后台登录密码：`demo123456`
+后端启动时会根据根目录 `.env` 自动确保默认管理员存在。
 
-> 说明：以上为 `seed_demo_data.py` 初始化的演示管理员账号（role=`admin`）。
+- 管理后台登录账号：`DEFAULT_ADMIN_PHONE` 或 `DEFAULT_ADMIN_EMAIL`
+- 管理后台登录密码：`DEFAULT_ADMIN_PASSWORD`
+
+默认模板值为 `13900000001 / admin123456`。生产环境请修改根目录 `.env`。
diff --git a/server/app/core/config.py b/server/app/core/config.py
index 0c4a517..74f70d9 100644
--- a/server/app/core/config.py
+++ b/server/app/core/config.py
@@ -34,6 +34,13 @@ class Settings(BaseSettings):
     LOG_JSON: bool = False
     LOG_LEVEL: str = "INFO"
 
+    DEFAULT_ADMIN_ENABLED: bool = True
+    DEFAULT_ADMIN_PHONE: str = "13900000001"
+    DEFAULT_ADMIN_EMAIL: str = "admin@ciyuan.local"
+    DEFAULT_ADMIN_PASSWORD: str = "admin123456"
+    DEFAULT_ADMIN_NICKNAME: str = "系统管理员"
+    DEFAULT_ADMIN_SYNC_PASSWORD: bool = True
+
     class Config:
         env_file = _env_file
 
diff --git a/server/app/db/bootstrap.py b/server/app/db/bootstrap.py
new file mode 100644
index 0000000..14dbadf
--- /dev/null
+++ b/server/app/db/bootstrap.py
@@ -0,0 +1,65 @@
+from sqlalchemy import or_, select
+from sqlalchemy.orm import Session
+
+from app.core.config import settings
+from app.core.security import get_password_hash, verify_password
+from app.db.session import sync_engine
+from app.models.user import User
+
+
+def ensure_default_admin() -> None:
+    if not settings.DEFAULT_ADMIN_ENABLED:
+        return
+
+    phone = settings.DEFAULT_ADMIN_PHONE.strip() or None
+    email = settings.DEFAULT_ADMIN_EMAIL.strip() or None
+    if not phone and not email:
+        raise RuntimeError("DEFAULT_ADMIN_PHONE or DEFAULT_ADMIN_EMAIL is required")
+
+    filters = []
+    if phone:
+        filters.append(User.phone == phone)
+    if email:
+        filters.append(User.email == email)
+
+    with Session(sync_engine) as session:
+        user = session.execute(select(User).where(or_(*filters))).scalar_one_or_none()
+
+        if user is None:
+            user = User(
+                phone=phone,
+                email=email,
+                password_hash=get_password_hash(settings.DEFAULT_ADMIN_PASSWORD),
+                nickname=settings.DEFAULT_ADMIN_NICKNAME,
+                identity="both",
+                role="admin",
+                is_active=True,
+            )
+            session.add(user)
+            session.commit()
+            return
+
+        changed = False
+        expected = {
+            "phone": phone,
+            "email": email,
+            "nickname": settings.DEFAULT_ADMIN_NICKNAME,
+            "identity": "both",
+            "role": "admin",
+            "is_active": True,
+        }
+        for field, value in expected.items():
+            if value is not None and getattr(user, field) != value:
+                setattr(user, field, value)
+                changed = True
+
+        if settings.DEFAULT_ADMIN_SYNC_PASSWORD and not verify_password(
+            settings.DEFAULT_ADMIN_PASSWORD,
+            user.password_hash,
+        ):
+            user.password_hash = get_password_hash(settings.DEFAULT_ADMIN_PASSWORD)
+            changed = True
+
+        if changed:
+            session.add(user)
+            session.commit()
diff --git a/server/app/main.py b/server/app/main.py
index 464e341..903cf23 100644
--- a/server/app/main.py
+++ b/server/app/main.py
@@ -14,6 +14,7 @@ from app.api.v1.router import v1_router
 from app.core.config import settings
 from app.core.deps import get_current_active_user, get_db
 from app.core.storage import init_storage
+from app.db.bootstrap import ensure_default_admin
 from app.db.migrations import run_startup_migrations
 from app.models.spot import Spot
 from app.models.tag import Tag
@@ -44,6 +45,7 @@ logger = logging.getLogger(__name__)
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     await asyncio.to_thread(run_startup_migrations)
+    await asyncio.to_thread(ensure_default_admin)
     app.state.redis = aioredis.from_url(settings.REDIS_URL, decode_responses=True)
     app.state.storage = init_storage()
     yield