diff --git a/web/src/pages/flow/canvas/index.tsx b/web/src/pages/flow/canvas/index.tsx
index b1f4864e9..f275fe267 100644
--- a/web/src/pages/flow/canvas/index.tsx
+++ b/web/src/pages/flow/canvas/index.tsx
@@ -16,11 +16,11 @@ import {
   useHandleKeyUp,
   useSelectCanvasData,
   useShowDrawer,
+  useValidateConnection,
 } from '../hooks';
 import { RagNode } from './node';
 
 import ChatDrawer from '../chat/drawer';
-import { isValidConnection } from '../utils';
 import styles from './index.less';
 import { BeginNode } from './node/begin-node';
 import { CategorizeNode } from './node/categorize-node';
@@ -49,6 +49,7 @@ function FlowCanvas({ chatDrawerVisible, hideChatDrawer }: IProps) {
     onNodesChange,
     onSelectionChange,
   } = useSelectCanvasData();
+  const isValidConnection = useValidateConnection();
 
   const { drawerVisible, hideDrawer, showDrawer, clickedNode } =
     useShowDrawer();
diff --git a/web/src/pages/flow/hooks.ts b/web/src/pages/flow/hooks.ts
index 2492edd2f..0b2d9ff49 100644
--- a/web/src/pages/flow/hooks.ts
+++ b/web/src/pages/flow/hooks.ts
@@ -13,7 +13,7 @@ import React, {
   useEffect,
   useState,
 } from 'react';
-import { Node, Position, ReactFlowInstance } from 'reactflow';
+import { Connection, Node, Position, ReactFlowInstance } from 'reactflow';
 // import { shallow } from 'zustand/shallow';
 import { variableEnabledFieldMap } from '@/constants/chat';
 import {
@@ -25,9 +25,9 @@ import { useDebounceEffect } from 'ahooks';
 import { FormInstance } from 'antd';
 import { humanId } from 'human-id';
 import { useParams } from 'umi';
-import { NodeMap, Operator } from './constant';
+import { NodeMap, Operator, RestrictedUpstreamMap } from './constant';
 import useGraphStore, { RFState } from './store';
-import { buildDslComponentsByGraph } from './utils';
+import { buildDslComponentsByGraph, getOperatorTypeFromId } from './utils';
 
 const selector = (state: RFState) => ({
   nodes: state.nodes,
@@ -247,3 +247,26 @@ export const useSetLlmSetting = (form?: FormInstance) => {
     form?.setFieldsValue({ ...switchBoxValues, ...otherValues });
   }, [form, initialLlmSetting]);
 };
+
+export const useValidateConnection = () => {
+  const edges = useGraphStore((state) => state.edges);
+  // restricted lines cannot be connected successfully.
+  const isValidConnection = useCallback(
+    (connection: Connection) => {
+      // limit there to be only one line between two nodes
+      const hasLine = edges.some(
+        (x) => x.source === connection.source && x.target === connection.target,
+      );
+
+      const ret =
+        !hasLine &&
+        RestrictedUpstreamMap[
+          getOperatorTypeFromId(connection.source) as Operator
+        ]?.every((x) => x !== getOperatorTypeFromId(connection.target));
+      return ret;
+    },
+    [edges],
+  );
+
+  return isValidConnection;
+};
diff --git a/web/src/pages/flow/utils.ts b/web/src/pages/flow/utils.ts
index b2a691616..e1e1e15cb 100644
--- a/web/src/pages/flow/utils.ts
+++ b/web/src/pages/flow/utils.ts
@@ -3,13 +3,9 @@ import { removeUselessFieldsFromValues } from '@/utils/form';
 import dagre from 'dagre';
 import { curry, isEmpty } from 'lodash';
 import pipe from 'lodash/fp/pipe';
-import { Connection, Edge, MarkerType, Node, Position } from 'reactflow';
+import { Edge, MarkerType, Node, Position } from 'reactflow';
 import { v4 as uuidv4 } from 'uuid';
-import {
-  Operator,
-  RestrictedUpstreamMap,
-  initialFormValuesMap,
-} from './constant';
+import { Operator, initialFormValuesMap } from './constant';
 import { NodeData } from './interface';
 
 const buildEdges = (
@@ -170,11 +166,3 @@ export const buildDslComponentsByGraph = (
 export const getOperatorTypeFromId = (id: string | null) => {
   return id?.split(':')[0] as Operator | undefined;
 };
-
-// restricted lines cannot be connected successfully.
-export const isValidConnection = (connection: Connection) => {
-  const ret = RestrictedUpstreamMap[
-    getOperatorTypeFromId(connection.source) as Operator
-  ]?.every((x) => x !== getOperatorTypeFromId(connection.target));
-  return ret;
-};