diff --git a/server/src/routes/logs.ts b/server/src/routes/logs.ts
index 5a95414..bd92ad0 100644
--- a/server/src/routes/logs.ts
+++ b/server/src/routes/logs.ts
@@ -111,8 +111,9 @@ router.get('/:date', requireAdmin, (req, res) => {
     let lines = content.split('\n').filter(l => l.trim())
 
     // 按级别过滤
-    if (level && level !== 'all') {
-      lines = lines.filter(l => l.includes(` ${level.toUpperCase()} `))
+    const levelStr = typeof level === 'string' ? level : ''
+    if (levelStr && levelStr !== 'all') {
+      lines = lines.filter(l => l.includes(` ${levelStr.toUpperCase()} `))
     }
 
     // 按关键词过滤