diff --git a/tf_adapter/optimizers/om_partition_subgraphs_pass.cc b/tf_adapter/optimizers/om_partition_subgraphs_pass.cc
index 3eced9e721fa508258f9bf8fa9f5e69a9887588c..70e0ff512d7c571ac80176b78e469b4640657988 100644
--- a/tf_adapter/optimizers/om_partition_subgraphs_pass.cc
+++ b/tf_adapter/optimizers/om_partition_subgraphs_pass.cc
@@ -87,6 +87,23 @@ void GetAccumulateBuilderInfo(Node *node, std::vector<tensorflow::NodeBuilder::N
   }
   delete_nodes.emplace_back(node);
 }
+
+void CacheClusterReachableStatus(const std::set<int> &clusterSet, tensorflow::GraphCycles &cycles,
+                                 std::vector<std::vector<bool>> &clusters_to_reachable) {
+  const size_t max_index = *clusterSet.rbegin() + 1;
+  clusters_to_reachable.resize(max_index);
+  for (size_t i = 0U; i < max_index; ++i) {
+    clusters_to_reachable[i].resize(max_index);
+  }
+  LOG(INFO) << "cluster set max index:" << *clusterSet.end();
+  for (int src : clusterSet) {
+    for (int dst : clusterSet) {
+      if (src == dst) { continue; }
+      LOG(INFO) << "cached src:" << src << " and dst:" << dst << "reachable result";
+      clusters_to_reachable[src][dst] = cycles.IsReachableNonConst(src, dst);
+    }
+  }
+}
 } // namespace
 static const int64 kMicrosToMillis = 1000;
 
@@ -832,9 +849,19 @@ Status MergeSubgraphsInNewWay(std::vector<std::pair<string, int>> &sortedCluster
     if (mergedClusters.count(dstSubgraph) < 1) {
       (void) mergedClusters.insert(dstSubgraph);
       for (const string &toMerge : clusterToMerge[dstSubgraph]) {
+        bool can_merge = true;
         if (clusterToMerge[toMerge].count(dstSubgraph) > 0) {
-          (void) mergedClusters.insert(toMerge);
-          mergePair[toMerge] = dstSubgraph;
+          for (const auto merged : mergePair) {
+            if (merged.second == dstSubgraph && (clusterToMerge[merged.first].count(toMerge) == 0 ||
+                                                 clusterToMerge[toMerge].count(merged.first) == 0)) {
+              can_merge = false;
+              break;
+            }
+          }
+          if (can_merge) {
+            mergePair[toMerge] = dstSubgraph;
+            (void) mergedClusters.insert(toMerge);
+          }
         }
       }
     }
@@ -1084,19 +1111,18 @@ Status MarkForPartition(const std::unique_ptr<Graph> *graph_in, int &clusterNum,
   }
   // Generate Merge possibility between clusters
   if (clusterSet.size() > 1) {
-    for (int src : clusterSet) {
-      for (int dst : clusterSet) {
+    std::vector<std::vector<bool>> clusters_to_reachable;
+    CacheClusterReachableStatus(clusterSet, cycles, clusters_to_reachable);
+    std::set<std::pair<int, int>> is_seen_clusters;
+    for (auto src_iter = clusterSet.begin(); src_iter != clusterSet.end(); ++src_iter) {
+      for (auto dst_iter = std::next(src_iter); dst_iter != clusterSet.end(); ++dst_iter) {
+        const int src = *src_iter;
+        const int dst = *dst_iter;
         if (src == dst) { continue; }
-        if (!cycles.IsReachableNonConst(src, dst) && !cycles.IsReachableNonConst(dst, src)) {
+        LOG(INFO) << "find result src:" << src << " and dst:" << dst;
+        if (!clusters_to_reachable[src][dst] && !clusters_to_reachable[dst][src]) {
           if (mix_compile_mode) {
             bool canReach = false;
-            for (auto cluster : clusterIndexToMerge[src]) {
-              if (cycles.IsReachableNonConst(dst, cluster) || cycles.IsReachableNonConst(cluster, dst)) {
-                canReach = true;
-                break;
-              }
-            }
-
             if (!canReach && job != "localhost") {
               Cluster *cluster_src = nullptr;
               Cluster *cluster_dst = nullptr;
@@ -1121,10 +1147,11 @@ Status MarkForPartition(const std::unique_ptr<Graph> *graph_in, int &clusterNum,
             }
             if (!canReach) {
               (void) clusterToMerge[clusterInfo[src].first].insert(clusterInfo[dst].first);
-              (void) clusterIndexToMerge[src].insert(dst);
+              (void) clusterToMerge[clusterInfo[dst].first].insert(clusterInfo[src].first);
             }
           } else {
             (void) clusterToMerge[clusterInfo[src].first].insert(clusterInfo[dst].first);
+            (void) clusterToMerge[clusterInfo[dst].first].insert(clusterInfo[src].first);
           }
         }
       }