diff --git a/app/api/v1/user.py b/app/api/v1/user.py
index dc23388..f310b2b 100644
--- a/app/api/v1/user.py
+++ b/app/api/v1/user.py
@@ -69,6 +69,18 @@ def complete_onboarding(
     return OkResponse()
 
 
+@router.post("/onboarding/reset", response_model=OkResponse, summary="重置新手引导(删该 设备+账号 完成标记,下次登录重走)")
+def reset_onboarding(
+    req: OnboardingCompleteRequest, user: CurrentUser, db: DbSession
+) -> OkResponse:
+    """删该 (当前账号, device_id) 的引导完成标记 → 下次登录 onboarding_completed=false,客户端重走。
+    与 /onboarding/complete 互逆。device_id 取客户端硬件级 ANDROID_ID(与登录/complete 一致)。
+    幂等:无记录也返回 ok。仅删自己(当前 JWT 用户)这台设备的记录,不影响别的账号/设备。"""
+    deleted = onboarding_repo.delete_completion(db, user_id=user.id, device_id=req.device_id)
+    logger.info("onboarding reset user_id=%d device_len=%d deleted=%d", user.id, len(req.device_id), deleted)
+    return OkResponse()
+
+
 @router.get(
     "/onboarding/status",
     response_model=OnboardingStatusResponse,
diff --git a/app/repositories/onboarding.py b/app/repositories/onboarding.py
index 03e51d3..0750dd1 100644
--- a/app/repositories/onboarding.py
+++ b/app/repositories/onboarding.py
@@ -5,7 +5,7 @@ device_id 为空(老客户端 / 取不到 ANDROID_ID)一律按"未完成"处理,
 """
 from __future__ import annotations
 
-from sqlalchemy import select
+from sqlalchemy import delete, select
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import Session
 
@@ -33,3 +33,18 @@ def mark_completed(db: Session, *, user_id: int, device_id: str) -> None:
     except IntegrityError:
         # 并发 / 重复提交撞唯一约束:已有行即视为成功。
         db.rollback()
+
+
+def delete_completion(db: Session, *, user_id: int, device_id: str) -> int:
+    """删该 (账号, 设备) 的引导完成标记 → 下次登录 is_completed=False → 客户端重走。
+    与 [mark_completed] 互逆。device_id 为空忽略(返 0);无记录也幂等(返 0)。返回删除行数。"""
+    if not device_id:
+        return 0
+    result = db.execute(
+        delete(OnboardingCompletion).where(
+            OnboardingCompletion.user_id == user_id,
+            OnboardingCompletion.device_id == device_id,
+        )
+    )
+    db.commit()
+    return result.rowcount
diff --git a/tests/test_onboarding.py b/tests/test_onboarding.py
index 3b6f533..a56c9f0 100644
--- a/tests/test_onboarding.py
+++ b/tests/test_onboarding.py
@@ -65,3 +65,28 @@ def test_onboarding_missing_device_id_treated_as_incomplete(client) -> None:
     phone = "13800138003"
     data = _login(client, phone, device_id=None)
     assert data["onboarding_completed"] is False
+
+
+def _reset(client, access: str, device_id: str):
+    return client.post(
+        "/api/v1/user/onboarding/reset",
+        json={"device_id": device_id},
+        headers={"Authorization": f"Bearer {access}"},
+    )
+
+
+def test_onboarding_reset_makes_relogin_reonboard(client) -> None:
+    """重置(删完成标记)后,同 (账号, 设备) 再登录 → onboarding_completed=False,重走引导。
+    对应客户端「开发设置 → 重置新手引导」:先删后端行,再退登录重开。"""
+    phone = "13800138004"
+    dev = "android-id-reset"
+
+    # ① 走完引导 → 标记完成 → 再登录已完成
+    access = _login(client, phone, dev)["access_token"]
+    assert _mark_complete(client, access, dev).status_code == 200
+    assert _login(client, phone, dev)["onboarding_completed"] is True
+
+    # ② 重置(幂等:重复重置也 200)→ 再登录变未完成 → 重走引导
+    assert _reset(client, access, dev).status_code == 200
+    assert _reset(client, access, dev).json()["ok"] is True
+    assert _login(client, phone, dev)["onboarding_completed"] is False