diff --git a/pkg/config/config.go b/pkg/config/config.go
index 84e1ab61a..b5205a24e 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -1416,17 +1416,29 @@ func LoadConfig(path string) (*Config, error) {
 		if err != nil {
 			return nil, err
 		}
-		// Load security configuration
-		securityPath := securityPath(path)
-		sec, err := loadSecurityConfig(securityPath)
+
+		// Legacy config (no version field)
+		tmpCfg, e := loadConfigV0(data)
+		if e != nil {
+			return nil, e
+		}
+
+		tmpCfgMigrated, e := tmpCfg.Migrate()
+		if e != nil {
+			logger.ErrorF("config migrate fail", map[string]any{"from": versionInfo.Version, "to": CurrentVersion})
+			return nil, e
+		}
+
+		// Load security configuration from .security.yml
+		secPath := securityPath(path)
+		sec, err := loadSecurityConfig(secPath)
 		if err != nil {
 			return nil, fmt.Errorf("failed to load security config: %w", err)
 		}
 
-		// Apply security references from .security.yml BEFORE resolveAPIKeys
-		// This resolves ref: references to actual values
-		if err := applySecurityConfig(cfg, sec); err != nil {
-			return nil, fmt.Errorf("failed to apply security config: %w", err)
+		// Merge security configs: config.json takes precedence over .security.yml
+		if err := applySecurityConfigWithPrecedence(cfg, tmpCfgMigrated, sec); err != nil {
+			return nil, fmt.Errorf("failed to merge security config: %w", err)
 		}
 	default:
 		return nil, fmt.Errorf("unsupported config version: %d", versionInfo.Version)
@@ -1688,6 +1700,28 @@ func applySecurityConfig(cfg *Config, sec *SecurityConfig) error {
 	return nil
 }
 
+// applySecurityConfigWithPrecedence merges security config from tmpCfg (migrated from configV0) and sec (SecurityConfig),
+// with tmpCfg taking precedence. It then applies the merged security config to cfg.
+func applySecurityConfigWithPrecedence(cfg *Config, tmpCfg *Config, sec *SecurityConfig) error {
+	// Get security config from tmpCfg (already extracted during migration)
+	var tmpSec *SecurityConfig
+	if tmpCfg != nil {
+		tmpSec = tmpCfg.security
+	}
+
+	// If tmpCfg has no security config, just apply sec directly
+	if tmpSec == nil {
+		return applySecurityConfig(cfg, sec)
+	}
+
+	// Merge sec and tmpSec, with tmpSec (from config.json) taking precedence
+	// mergeSecurityConfig(existing, newer) - newer takes precedence
+	mergedSec := mergeSecurityConfig(sec, tmpSec)
+
+	// Apply the merged security config to cfg
+	return applySecurityConfig(cfg, mergedSec)
+}
+
 func toNameIndex(list []*ModelConfig) []string {
 	nameList := make([]string, 0, len(list))
 	countMap := make(map[string]int)