diff --git a/packages/dag/src/EditorView.vue b/packages/dag/src/EditorView.vue
index 67dd7ec67..4c41bf8ec 100644
--- a/packages/dag/src/EditorView.vue
+++ b/packages/dag/src/EditorView.vue
@@ -54,6 +54,7 @@ const {
   onDeleteNode,
   onDeleteNodes,
   onAddNode,
+  canAddNode,
   onMoveNodePosition,
   onUpdateNodesPosition,
   onClickNode,
@@ -496,6 +497,7 @@ provide('dataflow', dataflow)
 provide('dataflowName', dataflowName)
 provide('dataflowDesc', dataflowDesc)
 provide('onNameInputChange', onNameInputChange)
+provide('canAddNode', canAddNode)
 provide('formScope', formScope)
 provide('isSaving', isSaving)
 provide('previewData', previewData)
diff --git a/packages/dag/src/MonitorView.vue b/packages/dag/src/MonitorView.vue
index 6b4533324..d87c72a9c 100644
--- a/packages/dag/src/MonitorView.vue
+++ b/packages/dag/src/MonitorView.vue
@@ -69,6 +69,7 @@ const {
   onDeleteNode,
   onDeleteNodes,
   onAddNode,
+  canAddNode,
   onMoveNodePosition,
   onUpdateNodesPosition,
   onClickNode,
@@ -641,6 +642,7 @@ provide('buttonShowMap', buttonShowMap)
 provide('dataflow', dataflow)
 provide('dataflowName', dataflowName)
 provide('dataflowDesc', dataflowDesc)
+provide('canAddNode', canAddNode)
 provide('onNameInputChange', onNameInputChange)
 provide('formScope', formScope)
 provide('isSaving', isSaving)
diff --git a/packages/dag/src/RecordView.vue b/packages/dag/src/RecordView.vue
index 506b14d35..137f1ab26 100644
--- a/packages/dag/src/RecordView.vue
+++ b/packages/dag/src/RecordView.vue
@@ -31,6 +31,7 @@ const {
   onDeleteNode,
   onDeleteNodes,
   onAddNode,
+  canAddNode,
   onMoveNodePosition,
   onUpdateNodesPosition,
   onClickNode,
@@ -65,6 +66,7 @@ provide('dataflow', dataflow)
 provide('dataflowName', dataflowName)
 provide('dataflowDesc', dataflowDesc)
 provide('onNameInputChange', onNameInputChange)
+provide('canAddNode', canAddNode)
 provide('formScope', formScope)
 provide('isSaving', isSaving)
 </script>
diff --git a/packages/dag/src/components/NodesPanel.vue b/packages/dag/src/components/NodesPanel.vue
index 19f5169e2..ede57d37d 100644
--- a/packages/dag/src/components/NodesPanel.vue
+++ b/packages/dag/src/components/NodesPanel.vue
@@ -26,9 +26,16 @@ const pageSize = 20
 const dataflow = inject<any>('dataflow')
 const isSyncTask = inject<any>('isSyncTask')
 const onAddNode = inject<(node: any) => void>('onAddNode')
+const canAddNode = inject<(node: any) => boolean>('canAddNode')
 const onCreateConnection =
   inject<(connection: any) => void>('onCreateConnection')
 
+const addNode = (node: any) => {
+  if (canAddNode && !canAddNode(node)) return false
+  onAddNode?.(node)
+  return true
+}
+
 const {
   dragNode,
   dragStarting,
@@ -37,7 +44,7 @@ const {
   onDragMove,
   onDragStop,
   onDrop,
-} = useDnD({ emit, onAddNode })
+} = useDnD({ emit, onAddNode: addNode })
 
 const showConnectionSearch = ref(false)
 const connectionSearchRef = ref<InstanceType<
@@ -297,7 +304,7 @@ const handleAddTable = async () => {
       node.attrs.position = [maxX + maxNodeWidth + X_OFFSET, maxY]
     }
 
-    onAddNode?.(node)
+    addNode(node)
   }
 }
 
@@ -396,13 +403,17 @@ const handleDblClickAddNode = (node: any) => {
   if (dataflowStore.stateIsReadonly) return
 
   historyStore.startRecordingUndo()
+  if (canAddNode && !canAddNode(node)) {
+    historyStore.stopRecordingUndo()
+    return
+  }
 
   const allNodes = dataflowStore.dag.nodes
 
   if (!allNodes.length) {
     // 画布为空，放到视口中心
     node.attrs.position = getViewportCenterPosition()
-    onAddNode?.(node)
+    addNode(node)
   } else {
     // 找到一个没有输出的节点作为上游
     const source = allNodes.find((n) => !n.$outputs || n.$outputs.length === 0)
@@ -427,12 +438,12 @@ const handleDblClickAddNode = (node: any) => {
       node.attrs.position = findNonOverlappingPosition(
         position as [number, number],
       )
-      onAddNode?.(node)
+      addNode(node)
       onCreateConnection?.({ source: source.id, target: node.id })
     } else {
       // 不能连线或没有可用上游：放到最右侧节点右边
       node.attrs.position = findNonOverlappingPosition(getRightmostPosition())
-      onAddNode?.(node)
+      addNode(node)
     }
   }
 
diff --git a/packages/dag/src/components/elements/NodesPopover.vue b/packages/dag/src/components/elements/NodesPopover.vue
index 45f10926f..5a497e29c 100644
--- a/packages/dag/src/components/elements/NodesPopover.vue
+++ b/packages/dag/src/components/elements/NodesPopover.vue
@@ -35,6 +35,7 @@ const historyStore = useHistoryStore()
 // Inject tracking functions for history support
 const dataflow = inject<Ref<any>>('dataflow')!
 const onAddNode = inject<(node: any) => void>('onAddNode')
+const canAddNode = inject<(node: any) => boolean>('canAddNode')
 const onCreateConnection =
   inject<(connection: any) => void>('onCreateConnection')
 const onDeleteConnection =
@@ -300,6 +301,10 @@ const handleAddNode = (node: any) => {
 
   // 开始批量记录 - 所有操作作为一个 BulkCommand
   historyStore.startRecordingUndo()
+  if (canAddNode && !canAddNode(node)) {
+    historyStore.stopRecordingUndo()
+    return
+  }
 
   if (nextNodeId && prevNodeId) {
     // 在两个节点之间添加
@@ -315,7 +320,6 @@ const handleAddNode = (node: any) => {
       historyStore.stopRecordingUndo()
       return
     }
-
     const afterNodes = dataflowStore.getAfterNodesInSameBranch(nextNodeId)
     const nextNode = findNode(nextNodeId)!
     const prevCanvasNode = findNode(prevNodeId)!
@@ -353,9 +357,7 @@ const handleAddNode = (node: any) => {
       target: nextNodeId,
     })
 
-    // 添加新节点
     onAddNode?.(node)
-
     // 添加新连线
     onCreateConnection?.({
       source: prevNodeId,
diff --git a/packages/dag/src/composables/useCanvasOperation.ts b/packages/dag/src/composables/useCanvasOperation.ts
index 61a71f009..2ebc5de60 100644
--- a/packages/dag/src/composables/useCanvasOperation.ts
+++ b/packages/dag/src/composables/useCanvasOperation.ts
@@ -548,7 +548,32 @@ export function useCanvasOperation() {
     historyStore.stopRecordingUndo()
   }
 
+  const isEnabledJoinNode = (node: any) =>
+    node?.type === 'join_processor' && !node.disabled && !node.attrs?.disabled
+
+  const getEnabledJoinNodeCount = () =>
+    dataflowStore.dag.nodes.filter(isEnabledJoinNode).length
+
+  const showJoinNodeLimitMessage = () => {
+    ElMessage.error(t('packages_dag_join_node_limit'))
+  }
+
+  const canAddJoinNodes = (count = 1) => {
+    if (!count) return true
+    return getEnabledJoinNodeCount() + count <= 1
+  }
+
+  const canAddNode = (node: any) => {
+    if (isEnabledJoinNode(node) && !canAddJoinNodes()) {
+      showJoinNodeLimitMessage()
+      return false
+    }
+    return true
+  }
+
   const onAddNode = (node: any, { trackHistory = true } = {}) => {
+    if (!canAddNode(node)) return false
+
     if (
       (node.type === 'table' || node.type === 'database') &&
       node.attrs?.pdkHash
@@ -587,6 +612,8 @@ export function useCanvasOperation() {
     if (trackHistory) {
       historyStore.pushCommandToUndo(new AddNodeCommand(node, Date.now()))
     }
+
+    return true
   }
 
   // ========== Copy / Paste ==========
@@ -687,6 +714,11 @@ export function useCanvasOperation() {
     const edges: any[] = cloneDeep(data.edges || [])
     if (!nodes.length) return []
 
+    if (!canAddJoinNodes(nodes.filter(isEnabledJoinNode).length)) {
+      showJoinNodeLimitMessage()
+      return []
+    }
+
     // 计算原始节点组的包围盒左上角
     let origMinX = Infinity
     let origMinY = Infinity
@@ -907,6 +939,13 @@ export function useCanvasOperation() {
     await Promise.all(nodes.map((node) => validateNode(node)))
   }
 
+  // --- Join 节点数量校验 ---
+  const validateJoin = () => {
+    return getEnabledJoinNodeCount() > 1
+      ? t('packages_dag_join_node_limit')
+      : ''
+  }
+
   // --- DAG 结构校验 ---
   const validateDag = () => {
     let someErrorMsg = ''
@@ -1456,6 +1495,7 @@ export function useCanvasOperation() {
     await validateAllNodes(nodes)
 
     return await eachValidate(
+      validateJoin,
       validateSetting,
       validateDag,
       validateAgent,
@@ -2140,6 +2180,7 @@ export function useCanvasOperation() {
     onDeleteNode,
     onDeleteNodes,
     onAddNode,
+    canAddNode,
     onCopyNodes,
     onPasteNodes,
     validate,
diff --git a/packages/dag/src/locale/lang/en.js b/packages/dag/src/locale/lang/en.js
index 8037b402d..b8ffce043 100644
--- a/packages/dag/src/locale/lang/en.js
+++ b/packages/dag/src/locale/lang/en.js
@@ -88,6 +88,8 @@ export default {
   packages_dag_editor_cell_validate_empty_name: 'Name is required.',
   packages_dag_editor_cell_validate_none_data_node:
     'At least 2 data node in graph',
+  packages_dag_join_node_limit:
+    'This task supports only one Join node. For multi-level Joins, write the first Join result to an intermediate table, then create a second task to read the intermediate table and perform the next Join.',
   packages_dag_dag_save_fail: 'Failed to save, please check the node.',
   packages_dag_message_operation_error: 'Operation Failed',
   packages_dag_message_resetOk: 'Reset Success',
diff --git a/packages/dag/src/locale/lang/zh-CN.js b/packages/dag/src/locale/lang/zh-CN.js
index 7baa9efa8..37c38d8ba 100644
--- a/packages/dag/src/locale/lang/zh-CN.js
+++ b/packages/dag/src/locale/lang/zh-CN.js
@@ -77,6 +77,8 @@ export default {
   packages_dag_task_list_button_monitor: '运行监控',
   packages_dag_editor_cell_validate_empty_name: '名称必填.',
   packages_dag_editor_cell_validate_none_data_node: '至少有两个数据节点',
+  packages_dag_join_node_limit:
+    '当前任务仅支持一个 Join 节点；如需多层 Join，请将第一层 Join 结果写入中间表，再创建第二个任务读取中间表并执行下一层 Join。',
   packages_dag_dag_save_fail: '保存出错，请检查节点',
   packages_dag_message_operation_error: '操作失败',
   packages_dag_message_resetOk: '重置成功',
diff --git a/packages/dag/src/locale/lang/zh-TW.js b/packages/dag/src/locale/lang/zh-TW.js
index fe33f1261..9759ea041 100644
--- a/packages/dag/src/locale/lang/zh-TW.js
+++ b/packages/dag/src/locale/lang/zh-TW.js
@@ -77,6 +77,8 @@ export default {
   packages_dag_task_list_button_monitor: '運行監控',
   packages_dag_editor_cell_validate_empty_name: '名稱必填.',
   packages_dag_editor_cell_validate_none_data_node: '至少有兩個數據節點',
+  packages_dag_join_node_limit:
+    '當前任務僅支持一個 Join 節點；如需多層 Join，請將第一層 Join 結果寫入中間表，再建立第二個任務讀取中間表並執行下一層 Join。',
   packages_dag_dag_save_fail: '保存出錯，請檢查節點',
   packages_dag_message_operation_error: '操作失敗',
   packages_dag_message_resetOk: '重置成功',