diff --git a/ge/graph/passes/mark_force_unknown_for_cond_pass.cc b/ge/graph/passes/mark_force_unknown_for_cond_pass.cc
index aa36a43b..a9b2c70f 100644
--- a/ge/graph/passes/mark_force_unknown_for_cond_pass.cc
+++ b/ge/graph/passes/mark_force_unknown_for_cond_pass.cc
@@ -145,17 +145,63 @@ void MarkForceUnknownForCondPass::MarkUnknownForSwitch(const NodePtr &node, std:
 /// @return
 ///
 void MarkForceUnknownForCondPass::MarkUnknownForSwitch(const std::map<NodePtr, std::vector<NodePtr>> &switch_groups) {
-  for (auto it = switch_groups.begin(); it != switch_groups.end(); ++it) {
-    const auto &op_node = it->first;
-    const auto &op_desc = op_node->GetOpDesc();
-    if (op_desc->HasAttr(ATTR_NAME_CONTROL_FLOW_GROUP)) {
-      continue;
+  // Step 0: no group assigned. such as:
+  // Merge1{id=0, group=} => {Switch1{id=1, group=}, Switch2{id=2, group=}}
+  // Merge2{id=3, group=} => {Switch1{id=1, group=}, Switch3{id=4, group=}}
+  // Merge3{id=5, group=} => {Switch4{id=6, group=}, Switch5{id=7, group=}}
+  // Merge4{id=8, group=} => {Switch1{id=1, group=}, Switch5{id=7, group=}}
+  std::map<int64_t, int64_t> unique_groups;
+  const auto GetGroupIndex = [&unique_groups](const NodePtr &merge, const std::vector<NodePtr> &switch_group) {
+    int64_t group_index = merge->GetOpDesc()->GetId();
+    std::set<int64_t> group_ids{group_index};
+    for (const auto &node : switch_group) {
+      if (AttrUtils::GetInt(node->GetOpDesc(), ATTR_NAME_CONTROL_FLOW_GROUP, group_index)) {
+        GELOGI("[%s] Get group from [%s], index[%ld]", merge->GetName().c_str(), node->GetName().c_str(), group_index);
+        group_ids.insert(group_index);
+      }
+    }
+
+    const auto it = unique_groups.find(group_index);
+    if (it != unique_groups.end()) {
+      group_index = it->second;
     }
 
-    int64_t group_index = op_desc->GetId();
-    SetControlFlowGroup(op_node, group_index);
-    for (const auto &n : it->second) {
-      SetControlFlowGroup(n, group_index);
+    for (auto id : group_ids) {
+      unique_groups[id] = group_index;
+    }
+
+    return group_index;
+  };
+
+  const auto SetGroupIndex = [](const NodePtr &merge, const std::vector<NodePtr> &switch_group, int64_t group_index) {
+    SetControlFlowGroup(merge, group_index);
+    for (const auto &node : switch_group) {
+      SetControlFlowGroup(node, group_index);
+    }
+  };
+
+  // Step 1: Set group index to merge, if switch already has group, use assigned group.
+  // Merge1{id=0, group=0} => {Switch1{id=1, group=0}, Switch2{id=2, group=0}}
+  // Merge2{id=3, group=0} => {Switch1{id=1, group=0}, Switch3{id=4, group=0}}
+  // Merge3{id=5, group=5} => {Switch4{id=6, group=5}, Switch5{id=7, group=5}}
+  // Merge4{id=8, group=0} => {Switch1{id=1, group=0}, Switch5{id=7, group=0}}
+  for (const auto group : switch_groups) {
+    int64_t group_index = GetGroupIndex(group.first, group.second);
+    SetGroupIndex(group.first, group.second, group_index);
+  }
+
+  // Step 2: Adjust crossed merge group for unique group.
+  // Merge1{id=0, group=0} => {Switch1{id=1, group=0}, Switch2{id=2, group=0}}
+  // Merge2{id=3, group=0} => {Switch1{id=1, group=0}, Switch3{id=4, group=0}}
+  // Merge3{id=5, group=0} => {Switch4{id=6, group=0}, Switch5{id=7, group=0}}
+  // Merge4{id=8, group=0} => {Switch1{id=1, group=0}, Switch5{id=7, group=0}}
+  for (const auto group : switch_groups) {
+    int64_t group_index = -1;
+    (void)AttrUtils::GetInt(group.first->GetOpDesc(), ATTR_NAME_CONTROL_FLOW_GROUP, group_index);
+
+    const auto it = unique_groups.find(group_index);
+    if (it != unique_groups.end() && it->first != it->second) {
+      SetGroupIndex(group.first, group.second, it->second);
     }
   }
 }