diff --git a/frontend/src/api/index.ts b/frontend/src/api/index.ts
index 3915903..f2e573f 100644
--- a/frontend/src/api/index.ts
+++ b/frontend/src/api/index.ts
@@ -103,7 +103,7 @@ class Api {
   branchPlanOutline = (data: {
     branch_Number: number
     Modification_Requirement: string
-    Existing_Steps: string[]
+    Existing_Steps: IRawStepTask[]
     Baseline_Completion: number
     initialInputs: string[]
     goal: string
@@ -533,7 +533,7 @@ class Api {
   mockBranchPlanOutline = async (data: {
     branch_Number: number
     Modification_Requirement: string
-    Existing_Steps: string[]
+    Existing_Steps: IRawStepTask[]
     Baseline_Completion: number
     initialInputs: string[]
     goal: string
diff --git a/frontend/src/layout/components/Main/TaskTemplate/TaskSyllabus/Branch/PlanModification.vue b/frontend/src/layout/components/Main/TaskTemplate/TaskSyllabus/Branch/PlanModification.vue
index 124f73d..0f8186a 100644
--- a/frontend/src/layout/components/Main/TaskTemplate/TaskSyllabus/Branch/PlanModification.vue
+++ b/frontend/src/layout/components/Main/TaskTemplate/TaskSyllabus/Branch/PlanModification.vue
@@ -26,7 +26,7 @@
           />
         </template>
 
-        <!-- 自定义任务节点 -->
+        <!-- 任务节点 -->
         <template #node-task="nodeProps">
           <TaskNode
             :key="nodeProps.data.updateKey || nodeProps.id"
@@ -722,25 +722,12 @@ const handleAddBranch = async (taskId: string, branchContent: string) => {
         const generalGoal = agentsStore.agentRawPlan.data?.['General Goal'] || ''
         const initialInput = agentsStore.agentRawPlan.data?.['Initial Input Object'] || []
 
-        // 提取现有步骤名称
-        const existingSteps = collaborationProcess.value
-          .map(step => step.StepName)
-          .filter(Boolean) as string[]
-
-        // 计算基线完成度
-        const baselineCompletion =
-          collaborationProcess.value.length > 0
-            ? Math.round(
-                (collaborationProcess.value.length / collaborationProcess.value.length) * 100
-              )
-            : 0
-
-        // 调用 Mock API
+        // 根节点分支：从零开始生成完整方案
         const response = await api.mockBranchPlanOutline({
           branch_Number: 1,
           Modification_Requirement: branchContent,
-          Existing_Steps: existingSteps,
-          Baseline_Completion: baselineCompletion,
+          Existing_Steps: [],
+          Baseline_Completion: 0,
           initialInputs: Array.isArray(initialInput) ? initialInput : [initialInput],
           goal: generalGoal
         })
@@ -773,24 +760,12 @@ const handleAddBranch = async (taskId: string, branchContent: string) => {
         const generalGoal = agentsStore.agentRawPlan.data?.['General Goal'] || ''
         const initialInput = agentsStore.agentRawPlan.data?.['Initial Input Object'] || []
 
-        // 提取现有步骤名称
-        const existingSteps = collaborationProcess.value
-          .map(step => step.StepName)
-          .filter(Boolean) as string[]
-
-        // 计算基线完成度
-        const baselineCompletion =
-          collaborationProcess.value.length > 0
-            ? Math.round(
-                (collaborationProcess.value.length / collaborationProcess.value.length) * 100
-              )
-            : 0
-
+        //  根节点分支：从零开始生成完整方案
         const response = await api.branchPlanOutline({
           branch_Number: 1,
           Modification_Requirement: branchContent,
-          Existing_Steps: existingSteps,
-          Baseline_Completion: baselineCompletion,
+          Existing_Steps: [],
+          Baseline_Completion: 0,
           initialInputs: Array.isArray(initialInput) ? initialInput : [initialInput],
           goal: generalGoal
         })
@@ -911,25 +886,67 @@ const handleAddBranch = async (taskId: string, branchContent: string) => {
       const newBranchNodes: Node[] = []
       const newBranchEdges: Edge[] = []
 
+      // 🆕 判断父节点是否是分支节点
+      const parentIsBranchTask = parentNode.data.isBranchTask || false
+
       if (USE_MOCK_DATA) {
         // 使用 Mock API
         const generalGoal = agentsStore.agentRawPlan.data?.['General Goal'] || ''
         const initialInput = agentsStore.agentRawPlan.data?.['Initial Input Object'] || []
 
-        // 提取现有步骤名称
-        const existingSteps = collaborationProcess.value
-          .map(step => step.StepName)
-          .filter(Boolean) as string[]
+        // 🆕 根据父节点类型构建 existingSteps
+        let existingSteps: any[] = []
+        let baselineCompletion = 0
 
-        // 计算基线完成度
-        const baselineCompletion =
-          collaborationProcess.value.length > 0
-            ? Math.round(
-                (collaborationProcess.value.length / collaborationProcess.value.length) * 100
-              )
-            : 0
+        if (!parentIsBranchTask) {
+          // 父节点是主流程节点：传递主流程从 0 到父节点的步骤
+          const parentTaskIndex = collaborationProcess.value.findIndex(
+            task => task.StepName === parentNode.data.task.StepName
+          )
+          const parentIndex = parentTaskIndex >= 0 ? parentTaskIndex : 0
+
+          existingSteps = collaborationProcess.value.slice(0, parentIndex + 1).map(step => ({
+            StepName: step.StepName,
+            TaskContent: step.TaskContent,
+            InputObject_List: step.InputObject_List || [],
+            OutputObject: step.OutputObject || ''
+          }))
+
+          baselineCompletion =
+            collaborationProcess.value.length > 0
+              ? Math.round(((parentIndex + 1) / collaborationProcess.value.length) * 100)
+              : 0
+        } else {
+          // 父节点是分支节点：从分支数据中获取步骤
+          const branches = selectionStore.getAllFlowBranches()
+
+          // 找到父节点所属的分支
+          const parentBranch = branches.find(branch =>
+            branch.nodes.some(n => n.id === parentNode.id)
+          )
+
+          if (parentBranch && parentBranch.tasks) {
+            // 获取分支中从第一个节点到父节点的所有步骤
+            const parentIndexInBranch = parentBranch.nodes.findIndex(n => n.id === parentNode.id)
+            existingSteps = parentBranch.tasks.slice(0, parentIndexInBranch + 1).map(step => ({
+              StepName: step.StepName,
+              TaskContent: step.TaskContent,
+              InputObject_List: step.InputObject_List || [],
+              OutputObject: step.OutputObject || ''
+            }))
+
+            // 分支节点的基线完成度：根据主流程进度计算
+            const parentTaskIndex = collaborationProcess.value.findIndex(
+              task => task.StepName === parentNode.data.task.StepName
+            )
+            const parentIndex = parentTaskIndex >= 0 ? parentTaskIndex : 0
+            baselineCompletion =
+              collaborationProcess.value.length > 0
+                ? Math.round(((parentIndex + 1) / collaborationProcess.value.length) * 100)
+                : 0
+          }
+        }
 
-        // 调用 Mock API
         const response = await api.mockBranchPlanOutline({
           branch_Number: 1,
           Modification_Requirement: branchContent,
@@ -967,18 +984,58 @@ const handleAddBranch = async (taskId: string, branchContent: string) => {
         const generalGoal = agentsStore.agentRawPlan.data?.['General Goal'] || ''
         const initialInput = agentsStore.agentRawPlan.data?.['Initial Input Object'] || []
 
-        // 提取现有步骤名称
-        const existingSteps = collaborationProcess.value
-          .map(step => step.StepName)
-          .filter(Boolean) as string[]
+        // 🆕 根据父节点类型构建 existingSteps
+        let existingSteps: any[] = []
+        let baselineCompletion = 0
 
-        // 计算基线完成度
-        const baselineCompletion =
-          collaborationProcess.value.length > 0
-            ? Math.round(
-                (collaborationProcess.value.length / collaborationProcess.value.length) * 100
-              )
-            : 0
+        if (!parentIsBranchTask) {
+          // 父节点是主流程节点：传递主流程从 0 到父节点的步骤
+          const parentTaskIndex = collaborationProcess.value.findIndex(
+            task => task.StepName === parentNode.data.task.StepName
+          )
+          const parentIndex = parentTaskIndex >= 0 ? parentTaskIndex : 0
+
+          existingSteps = collaborationProcess.value.slice(0, parentIndex + 1).map(step => ({
+            StepName: step.StepName,
+            TaskContent: step.TaskContent,
+            InputObject_List: step.InputObject_List || [],
+            OutputObject: step.OutputObject || ''
+          }))
+
+          baselineCompletion =
+            collaborationProcess.value.length > 0
+              ? Math.round(((parentIndex + 1) / collaborationProcess.value.length) * 100)
+              : 0
+        } else {
+          // 父节点是分支节点：从分支数据中获取步骤
+          const branches = selectionStore.getAllFlowBranches()
+
+          // 找到父节点所属的分支
+          const parentBranch = branches.find(branch =>
+            branch.nodes.some(n => n.id === parentNode.id)
+          )
+
+          if (parentBranch && parentBranch.tasks) {
+            // 获取分支中从第一个节点到父节点的所有步骤
+            const parentIndexInBranch = parentBranch.nodes.findIndex(n => n.id === parentNode.id)
+            existingSteps = parentBranch.tasks.slice(0, parentIndexInBranch + 1).map(step => ({
+              StepName: step.StepName,
+              TaskContent: step.TaskContent,
+              InputObject_List: step.InputObject_List || [],
+              OutputObject: step.OutputObject || ''
+            }))
+
+            // 分支节点的基线完成度：根据主流程进度计算
+            const parentTaskIndex = collaborationProcess.value.findIndex(
+              task => task.StepName === parentNode.data.task.StepName
+            )
+            const parentIndex = parentTaskIndex >= 0 ? parentTaskIndex : 0
+            baselineCompletion =
+              collaborationProcess.value.length > 0
+                ? Math.round(((parentIndex + 1) / collaborationProcess.value.length) * 100)
+                : 0
+          }
+        }
 
         const response = await api.branchPlanOutline({
           branch_Number: 1,
@@ -989,11 +1046,10 @@ const handleAddBranch = async (taskId: string, branchContent: string) => {
           goal: generalGoal
         })
 
+        console.log('API Response:', response)
         // 直接获取协作流程数据（API 返回二维数组 [[task1, task2, ...]]，取第一个分支）
         newTasks = response?.[0] || []
-
-        // 调试日志：验证数据提取
-
+        console.log('获取到的新newTasks:', newTasks)
         // ========== 填充每个任务的 TaskProcess ==========
         for (let i = 0; i < newTasks.length; i++) {
           const task = newTasks[i]
diff --git a/frontend/src/layout/components/Main/TaskTemplate/TaskSyllabus/Branch/mock/branchPlanOutlineMock.ts b/frontend/src/layout/components/Main/TaskTemplate/TaskSyllabus/Branch/mock/branchPlanOutlineMock.ts
index 04be719..cf22b72 100644
--- a/frontend/src/layout/components/Main/TaskTemplate/TaskSyllabus/Branch/mock/branchPlanOutlineMock.ts
+++ b/frontend/src/layout/components/Main/TaskTemplate/TaskSyllabus/Branch/mock/branchPlanOutlineMock.ts
@@ -189,7 +189,7 @@ function generateCollaborationBrief(task: IRawStepTask): {
  *
  * @param branch_Number - 分支数量
  * @param Modification_Requirement - 修改需求
- * @param Existing_Steps - 现有步骤名称列表
+ * @param Existing_Steps - 现有步骤列表（包含完整信息的对象数组）
  * @param Baseline_Completion - 基线完成度
  * @param InitialObject_List - 初始对象列表
  * @param General_Goal - 总体目标
@@ -198,7 +198,7 @@ function generateCollaborationBrief(task: IRawStepTask): {
 export const mockBranchPlanOutlineAPI = async (params: {
   branch_Number: number
   Modification_Requirement: string
-  Existing_Steps: string[]
+  Existing_Steps: any[]  // 临时使用 any[]，因为这里没有 IRawStepTask 类型
   Baseline_Completion: number
   InitialObject_List: string[]
   General_Goal: string
@@ -221,7 +221,7 @@ export const mockBranchPlanOutlineAPI = async (params: {
   // 保存本次的选择索引
   sessionStorage.setItem(sessionKey, selectedBranchIndex.toString())
 
-  const rawBranchData = mockBranchDataRaw[selectedBranchIndex]
+  const rawBranchData = mockBranchDataRaw[selectedBranchIndex] || []
 
   console.log(
     '[Mock API] branch_PlanOutline 选择分支方案:',