diff --git a/internal/handler/config.go b/internal/handler/config.go
index adf998a6..0b604330 100644
--- a/internal/handler/config.go
+++ b/internal/handler/config.go
@@ -269,16 +269,12 @@ func (h *ConfigHandler) GetConfig(c *gin.Context) {
 	}
 	multiPub := config.MultiAgentPublic{
 		Enabled:                      h.config.MultiAgent.Enabled,
-		DefaultMode:                  h.config.MultiAgent.DefaultMode,
 		RobotUseMultiAgent:           h.config.MultiAgent.RobotUseMultiAgent,
 		BatchUseMultiAgent:           h.config.MultiAgent.BatchUseMultiAgent,
 		SubAgentCount:                subAgentCount,
 		Orchestration:                config.NormalizeMultiAgentOrchestration(h.config.MultiAgent.Orchestration),
 		PlanExecuteLoopMaxIterations: h.config.MultiAgent.PlanExecuteLoopMaxIterations,
 	}
-	if strings.TrimSpace(multiPub.DefaultMode) == "" {
-		multiPub.DefaultMode = "single"
-	}
 
 	c.JSON(http.StatusOK, GetConfigResponse{
 		OpenAI:     h.config.OpenAI,
@@ -686,10 +682,6 @@ func (h *ConfigHandler) UpdateConfig(c *gin.Context) {
 	// 多代理标量（sub_agents 等仍由 config.yaml 维护）
 	if req.MultiAgent != nil {
 		h.config.MultiAgent.Enabled = req.MultiAgent.Enabled
-		dm := strings.TrimSpace(req.MultiAgent.DefaultMode)
-		if dm == "multi" || dm == "single" {
-			h.config.MultiAgent.DefaultMode = dm
-		}
 		h.config.MultiAgent.RobotUseMultiAgent = req.MultiAgent.RobotUseMultiAgent
 		h.config.MultiAgent.BatchUseMultiAgent = req.MultiAgent.BatchUseMultiAgent
 		if req.MultiAgent.PlanExecuteLoopMaxIterations != nil {
@@ -697,7 +689,6 @@ func (h *ConfigHandler) UpdateConfig(c *gin.Context) {
 		}
 		h.logger.Info("更新多代理配置",
 			zap.Bool("enabled", h.config.MultiAgent.Enabled),
-			zap.String("default_mode", h.config.MultiAgent.DefaultMode),
 			zap.Bool("robot_use_multi_agent", h.config.MultiAgent.RobotUseMultiAgent),
 			zap.Bool("batch_use_multi_agent", h.config.MultiAgent.BatchUseMultiAgent),
 			zap.Int("plan_execute_loop_max_iterations", h.config.MultiAgent.PlanExecuteLoopMaxIterations),
@@ -1345,7 +1336,6 @@ func updateMultiAgentConfig(doc *yaml.Node, cfg config.MultiAgentConfig) {
 	root := doc.Content[0]
 	maNode := ensureMap(root, "multi_agent")
 	setBoolInMap(maNode, "enabled", cfg.Enabled)
-	setStringInMap(maNode, "default_mode", cfg.DefaultMode)
 	setBoolInMap(maNode, "robot_use_multi_agent", cfg.RobotUseMultiAgent)
 	setBoolInMap(maNode, "batch_use_multi_agent", cfg.BatchUseMultiAgent)
 	setIntInMap(maNode, "plan_execute_loop_max_iterations", cfg.PlanExecuteLoopMaxIterations)