diff --git a/app/core/security.py b/app/core/security.py
index adc9a328..1ac1594d 100644
--- a/app/core/security.py
+++ b/app/core/security.py
@@ -188,12 +188,19 @@ def set_or_refresh_resource_token_cookie(
         purpose="resource"
     )
 
+    # 判断请求是否为 HTTPS：直连协议为 https，或经反向代理转发时携带 X-Forwarded-Proto: https。
+    # 无法确认为明文 HTTP 时按 fail-safe 默认设置 secure=True，避免代理终止 HTTPS 后以 HTTP 转发导致 Cookie 明文传输。
+    is_https = (
+        request.url.scheme == "https"
+        or request.headers.get("x-forwarded-proto", "").lower() == "https"
+    )
+
     # 设置会话级别的 HttpOnly Cookie
     response.set_cookie(
         key=settings.PROJECT_NAME,
         value=resource_token,
         httponly=True,
-        secure=request.url.scheme == "https",  # 根据当前请求的协议设置 secure 属性
+        secure=is_https,  # 根据当前请求协议（含反向代理转发标识）设置 secure 属性
         samesite="lax"  # 不同浏览器对 "Strict" 的处理可能不同，设置 SameSite 为 "Lax"，以平衡安全性和兼容性
     )
 
diff --git a/tests/test_resource_token_cookie_secure_flag.py b/tests/test_resource_token_cookie_secure_flag.py
new file mode 100644
index 00000000..48c49de3
--- /dev/null
+++ b/tests/test_resource_token_cookie_secure_flag.py
@@ -0,0 +1,38 @@
+from unittest import TestCase
+
+from fastapi import Response
+
+from app import schemas
+from app.core.security import set_or_refresh_resource_token_cookie
+
+
+class FakeURL:
+    def __init__(self, scheme: str) -> None:
+        self.scheme = scheme
+
+
+class FakeRequest:
+    """
+    最小化的请求桩对象，仅提供 set_or_refresh_resource_token_cookie 所需属性。
+    """
+
+    def __init__(self, scheme: str, headers: dict | None = None) -> None:
+        self.url = FakeURL(scheme)
+        self.headers = headers or {}
+        self.cookies: dict = {}
+
+
+class ResourceTokenCookieSecureFlagTest(TestCase):
+    def test_secure_flag_set_when_https_terminated_at_reverse_proxy(self):
+        """
+        当反向代理（如 nginx）终止 HTTPS 并以 HTTP 转发给后端时，
+        资源令牌 Cookie 仍必须携带 secure 属性，不能因为直连请求协议是 http 就降级。
+        """
+        request = FakeRequest(scheme="http", headers={"x-forwarded-proto": "https"})
+        response = Response()
+        payload = schemas.TokenPayload(sub=1, username="test", super_user=False, level=1)
+
+        set_or_refresh_resource_token_cookie(request, response, payload)
+
+        set_cookie_header = response.headers.get("set-cookie", "")
+        self.assertIn("Secure", set_cookie_header)