diff --git a/scheduler/upgrade_cfg.cpp b/scheduler/upgrade_cfg.cpp
index 2beb7cb..3ddcce8 100644
--- a/scheduler/upgrade_cfg.cpp
+++ b/scheduler/upgrade_cfg.cpp
@@ -12,6 +12,14 @@ int UpgradeCfg::ReadCfg(std::map<int, UpgradeInfo> &upgrade) {
         zlog_info(zbt, "[UpgradeCfg] no such file");
         return 0;
     }
+    upgrade_file.seekg(0, std::ios::end);
+    std::streampos file_size = upgrade_file.tellg();
+    if (file_size > 256000) {
+        zlog_error(zct, "upgrade file exception, will remove it");
+        ClearCfg();
+        return 1;
+    }
+    upgrade_file.seekg(0, std::ios::beg);
 
     Json::Reader reader;
     Json::Value root;
@@ -51,6 +59,11 @@ int UpgradeCfg::ReadCfg(std::map<int, UpgradeInfo> &upgrade) {
 }
 
 int UpgradeCfg::WriteCfg(std::map<int, UpgradeInfo> &upgrade) {
+    if (upgrade.size() == 0) {
+        ClearCfg();
+        return 0;
+    }
+
     Json::Value root;        
     for (auto item : upgrade) {
         Json::Value upgrade_item;