diff --git a/web/app/components/workflow/hooks/use-checklist.ts b/web/app/components/workflow/hooks/use-checklist.ts
index 200bee1d26..47ebaa6710 100644
--- a/web/app/components/workflow/hooks/use-checklist.ts
+++ b/web/app/components/workflow/hooks/use-checklist.ts
@@ -9,6 +9,7 @@ import type {
   CommonNodeType,
   Edge,
   Node,
+  ValueSelector,
 } from '../types'
 import { BlockEnum } from '../types'
 import { useStore } from '../store'
@@ -33,6 +34,8 @@ import type { KnowledgeRetrievalNodeType } from '../nodes/knowledge-retrieval/ty
 import type { DataSet } from '@/models/datasets'
 import { fetchDatasets } from '@/service/datasets'
 import { MAX_TREE_DEPTH } from '@/config'
+import useNodesAvailableVarList from './use-nodes-available-var-list'
+import { getNodeUsedVars, isConversationVar, isENV, isSystemVar } from '../nodes/_base/components/variable/utils'
 
 export const useChecklist = (nodes: Node[], edges: Edge[]) => {
   const { t } = useTranslation()
@@ -45,6 +48,8 @@ export const useChecklist = (nodes: Node[], edges: Edge[]) => {
   const { data: strategyProviders } = useStrategyProviders()
   const datasetsDetail = useDatasetsDetailStore(s => s.datasetsDetail)
 
+  const map = useNodesAvailableVarList(nodes)
+
   const getCheckData = useCallback((data: CommonNodeType<{}>) => {
     let checkData = data
     if (data.type === BlockEnum.KnowledgeRetrieval) {
@@ -70,6 +75,7 @@ export const useChecklist = (nodes: Node[], edges: Edge[]) => {
       const node = nodes[i]
       let toolIcon
       let moreDataForCheckValid
+      let usedVars: ValueSelector[] = []
 
       if (node.data.type === BlockEnum.Tool) {
         const { provider_type } = node.data
@@ -84,8 +90,7 @@ export const useChecklist = (nodes: Node[], edges: Edge[]) => {
         if (provider_type === CollectionType.workflow)
           toolIcon = workflowTools.find(tool => tool.id === node.data.provider_id)?.icon
       }
-
-      if (node.data.type === BlockEnum.Agent) {
+      else if (node.data.type === BlockEnum.Agent) {
         const data = node.data as AgentNodeType
         const isReadyForCheckValid = !!strategyProviders
         const provider = strategyProviders?.find(provider => provider.declaration.identity.name === data.agent_strategy_provider_name)
@@ -97,10 +102,34 @@ export const useChecklist = (nodes: Node[], edges: Edge[]) => {
           isReadyForCheckValid,
         }
       }
+      else {
+        usedVars = getNodeUsedVars(node).filter(v => v.length > 0)
+      }
 
       if (node.type === CUSTOM_NODE) {
         const checkData = getCheckData(node.data)
-        const { errorMessage } = nodesExtraData[node.data.type].checkValid(checkData, t, moreDataForCheckValid)
+        let { errorMessage } = nodesExtraData[node.data.type].checkValid(checkData, t, moreDataForCheckValid)
+
+        if (!errorMessage) {
+          const availableVars = map[node.id].availableVars
+
+          for (const variable of usedVars) {
+            const isEnv = isENV(variable)
+            const isConvVar = isConversationVar(variable)
+            const isSysVar = isSystemVar(variable)
+            if (!isEnv && !isConvVar && !isSysVar) {
+              const usedNode = availableVars.find(v => v.nodeId === variable?.[0])
+              if (usedNode) {
+                const usedVar = usedNode.vars.find(v => v.variable === variable?.[1])
+                if (!usedVar)
+                  errorMessage = t('workflow.errorMsg.invalidVariable')
+              }
+              else {
+                errorMessage = t('workflow.errorMsg.invalidVariable')
+              }
+            }
+          }
+        }
 
         if (errorMessage || !validNodes.find(n => n.id === node.id)) {
           list.push({
diff --git a/web/app/components/workflow/hooks/use-nodes-available-var-list.ts b/web/app/components/workflow/hooks/use-nodes-available-var-list.ts
new file mode 100644
index 0000000000..5efe2519ef
--- /dev/null
+++ b/web/app/components/workflow/hooks/use-nodes-available-var-list.ts
@@ -0,0 +1,75 @@
+import {
+  useIsChatMode,
+  useWorkflow,
+  useWorkflowVariables,
+} from '@/app/components/workflow/hooks'
+import { BlockEnum, type Node, type NodeOutPutVar, type ValueSelector, type Var } from '@/app/components/workflow/types'
+type Params = {
+  onlyLeafNodeVar?: boolean
+  hideEnv?: boolean
+  hideChatVar?: boolean
+  filterVar: (payload: Var, selector: ValueSelector) => boolean
+  passedInAvailableNodes?: Node[]
+}
+
+const getNodeInfo = (nodeId: string, nodes: Node[]) => {
+  const allNodes = nodes
+  const node = allNodes.find(n => n.id === nodeId)
+  const isInIteration = !!node?.data.isInIteration
+  const isInLoop = !!node?.data.isInLoop
+  const parentNodeId = node?.parentId
+  const parentNode = allNodes.find(n => n.id === parentNodeId)
+  return {
+    node,
+    isInIteration,
+    isInLoop,
+    parentNode,
+  }
+}
+
+// TODO: loop type?
+const useNodesAvailableVarList = (nodes: Node[], {
+  onlyLeafNodeVar,
+  filterVar,
+  hideEnv = false,
+  hideChatVar = false,
+  passedInAvailableNodes,
+}: Params = {
+    onlyLeafNodeVar: false,
+    filterVar: () => true,
+  }) => {
+  const { getTreeLeafNodes, getBeforeNodesInSameBranchIncludeParent } = useWorkflow()
+  const { getNodeAvailableVars } = useWorkflowVariables()
+  const isChatMode = useIsChatMode()
+
+  const nodeAvailabilityMap: { [key: string ]: { availableVars: NodeOutPutVar[], availableNodes: Node[] } } = {}
+
+  nodes.forEach((node) => {
+    const nodeId = node.id
+    const availableNodes = passedInAvailableNodes || (onlyLeafNodeVar ? getTreeLeafNodes(nodeId) : getBeforeNodesInSameBranchIncludeParent(nodeId))
+    if (node.data.type === BlockEnum.Loop)
+      availableNodes.push(node)
+
+    const {
+      parentNode: iterationNode,
+    } = getNodeInfo(nodeId, nodes)
+
+    const availableVars = getNodeAvailableVars({
+      parentNode: iterationNode,
+      beforeNodes: availableNodes,
+      isChatMode,
+      filterVar,
+      hideEnv,
+      hideChatVar,
+    })
+    const result = {
+      node,
+      availableVars,
+      availableNodes,
+    }
+    nodeAvailabilityMap[nodeId] = result
+  })
+  return nodeAvailabilityMap
+}
+
+export default useNodesAvailableVarList
diff --git a/web/app/components/workflow/nodes/_base/components/variable/utils.ts b/web/app/components/workflow/nodes/_base/components/variable/utils.ts
index a69f9a51a7..7bd78ec6b6 100644
--- a/web/app/components/workflow/nodes/_base/components/variable/utils.ts
+++ b/web/app/components/workflow/nodes/_base/components/variable/utils.ts
@@ -948,9 +948,7 @@ export const getNodeUsedVars = (node: Node): ValueSelector[] => {
       break
     }
     case BlockEnum.Answer: {
-      res = (data as AnswerNodeType).variables?.map((v) => {
-        return v.value_selector
-      })
+      res = matchNotSystemVars([(data as AnswerNodeType).answer])
       break
     }
     case BlockEnum.LLM: {