diff --git a/app/main.py b/app/main.py
index bfb3517..be4c13d 100644
--- a/app/main.py
+++ b/app/main.py
@@ -60,6 +60,10 @@ async def lifespan(app: FastAPI):
     # Startup
     setup_logging()
     logger.info(f"Starting {settings.APP_NAME} v{settings.APP_VERSION}")
+    if not (settings.PUBLIC_BASE_URL or "").strip():
+        logger.warning(
+            "PUBLIC_BASE_URL 未设置，data.video_url 将按请求 Host 推导，跨机调用会拿到不可用地址"
+        )
     init_db()
     logger.info("Database initialized")
     _cleanup_expired_data()
diff --git a/tests/test_public_base_url_warning.py b/tests/test_public_base_url_warning.py
new file mode 100644
index 0000000..41f4b2e
--- /dev/null
+++ b/tests/test_public_base_url_warning.py
@@ -0,0 +1,39 @@
+import pytest
+from fastapi.testclient import TestClient
+
+from app.core.config import settings
+from app.main import app
+
+
+def _get_log_lines(tmp_path, pattern):
+    log_files = list(tmp_path.glob("app_*.log"))
+    assert len(log_files) == 1, f"Expected 1 app log file, found {len(log_files)}"
+    content = log_files[0].read_text(encoding="utf-8")
+    return [line for line in content.splitlines() if pattern in line]
+
+
+@pytest.mark.parametrize("empty_val", ["", "   "])
+def test_public_base_url_warning_when_empty(monkeypatch, tmp_path, empty_val):
+    monkeypatch.setattr(settings, "LOG_FILE_PATH", str(tmp_path))
+    monkeypatch.setattr(settings, "PUBLIC_BASE_URL", empty_val)
+
+    with TestClient(app, raise_server_exceptions=False) as client:
+        resp = client.get("/")
+        assert resp.status_code == 200
+        assert resp.json().get("status") == "running"
+
+    matches = _get_log_lines(tmp_path, "PUBLIC_BASE_URL 未设置")
+    assert len(matches) == 1
+    assert "data.video_url 将按请求 Host 推导，跨机调用会拿到不可用地址" in matches[0]
+
+
+def test_public_base_url_no_warning_when_set(monkeypatch, tmp_path):
+    monkeypatch.setattr(settings, "LOG_FILE_PATH", str(tmp_path))
+    monkeypatch.setattr(settings, "PUBLIC_BASE_URL", "https://api.example.com")
+
+    with TestClient(app, raise_server_exceptions=False) as client:
+        resp = client.get("/")
+        assert resp.status_code == 200
+
+    matches = _get_log_lines(tmp_path, "PUBLIC_BASE_URL 未设置")
+    assert len(matches) == 0