diff --git a/src/gausskernel/ddes/adapter/ss_dms_callback.cpp b/src/gausskernel/ddes/adapter/ss_dms_callback.cpp
index 1ed0dd5bb..45001113e 100644
--- a/src/gausskernel/ddes/adapter/ss_dms_callback.cpp
+++ b/src/gausskernel/ddes/adapter/ss_dms_callback.cpp
@@ -352,13 +352,27 @@ static inline void SSResetDemoteReqType(void)
     SpinLockRelease(&t_thrd.walsender_cxt.WalSndCtl->mutex);
 }
 
-static void SSHandleReformFailDuringDemote(DemoteMode demote_mode)
+static void SSHandleReformFailDuringDemote(bool timeout, DemoteMode demote_mode)
 {
     ereport(WARNING,
         (errmodule(MOD_DMS),
             errmsg("[SS reform][SS switchover] Failure in %s primary demote, pmState=%d, need reform rcy.",
                 DemoteModeDesc(demote_mode), pmState)));
 
+    if (timeout) {
+        g_instance.dms_cxt.SSReformInfo.switchover_demote_failure_signal_handled = false;
+        pg_memory_barrier();
+        SendPostmasterSignal(PMSIGNAL_DMS_SWITCHOVER_DEMOTE_FAILURE_CHECK);
+        const int WAIT_SIGNAL_HANDLED = 100; /* only wait 10s*/
+        for (int ntries = 0; ntries < WAIT_SIGNAL_HANDLED; ntries++) {
+            if (g_instance.dms_cxt.SSReformInfo.switchover_demote_failure_signal_handled) {
+                break;
+            }
+            CHECK_FOR_INTERRUPTS();
+            pg_usleep(100000L); /* wait 0.1 sec, then retry */
+        }
+    }
+
     /*
      * Shutdown checkpoint would cause concurrency as DMS is starting next round of reform.
      * If we allow ckpt to finish and recover, DMS would not be aware of the recovery process.
@@ -413,10 +427,10 @@ static int CBSwitchoverDemote(void *db_handle)
             return DMS_SUCCESS;
         } else {
             if (ntries >= WAIT_DEMOTE || dms_reform_failed()) {
-                SSHandleReformFailDuringDemote(demote_mode);
+                bool timeout = ntries >= WAIT_DEMOTE ? true : false;
+                SSHandleReformFailDuringDemote(timeout, demote_mode);
                 return DMS_ERROR;
             }
-            ntries = 0;
         }
 
         CHECK_FOR_INTERRUPTS();
diff --git a/src/gausskernel/process/postmaster/postmaster.cpp b/src/gausskernel/process/postmaster/postmaster.cpp
index 1878f0d34..16ae58749 100644
--- a/src/gausskernel/process/postmaster/postmaster.cpp
+++ b/src/gausskernel/process/postmaster/postmaster.cpp
@@ -10695,6 +10695,34 @@ static void sigusr1_handler(SIGNAL_ARGS)
         }
     }
 
+    if (ENABLE_DMS && CheckPostmasterSignal(PMSIGNAL_DMS_SWITCHOVER_DEMOTE_FAILURE_CHECK)) {
+        if (pmState == PM_WAIT_BACKENDS) {
+            int backend_count = SSCountAndPrintChildren(BACKEND_TYPE_NORMAL | BACKEND_TYPE_AUTOVAC);
+            if (backend_count > 0) {
+                ereport(WARNING, (errmodule(MOD_DMS), 
+                    errmsg("[SS reform][SS switchover] demote fail reason: backends exist, backend_count:%d, "
+                        "pmState:%d",
+                        backend_count, pmState)));
+            }
+
+            const int check_list_num = 4;
+            ThreadId check_list[check_list_num] = {
+                g_instance.pid_cxt.AshPID,
+                g_instance.pid_cxt.TwoPhaseCleanerPID,
+                g_instance.pid_cxt.StatementPID,
+                g_instance.pid_cxt.PercentilePID
+            };
+            for (int i = 0; i < check_list_num; i++) {
+                if (check_list[i] != 0 ) {
+                    ereport(WARNING, (errmodule(MOD_DMS), 
+                        errmsg("[SS reform][SS switchover] demote fail reason: thread name:%s exist, pid:%lu, pmState:%d",
+                            GetProcName(check_list[i]), check_list[i], pmState)));
+                }
+            }
+            g_instance.dms_cxt.SSReformInfo.switchover_demote_failure_signal_handled = true;
+        }
+    }
+
     if (CheckPromoteSignal()) {
         handle_promote_signal();
     }
@@ -15429,7 +15457,7 @@ int SSCountAndPrintChildren(int target)
     
         cnt++;
         ereport(WARNING, (errmodule(MOD_DMS),
-                errmsg("[SS reform][SS failover] print thread no exiting, thread id:%lu, thread role:%d",
+                errmsg("[SS reform] print thread no exiting, thread id:%lu, thread role:%d",
                 bp->pid, bp->role)));
     }
 
diff --git a/src/gausskernel/process/threadpool/knl_instance.cpp b/src/gausskernel/process/threadpool/knl_instance.cpp
index c1ba0b33d..d5358fe26 100755
--- a/src/gausskernel/process/threadpool/knl_instance.cpp
+++ b/src/gausskernel/process/threadpool/knl_instance.cpp
@@ -193,6 +193,7 @@ static void knl_g_dms_init(knl_g_dms_context *dms_cxt)
     dms_cxt->SSReformInfo.redo_total_bytes = 0;
     dms_cxt->SSReformInfo.reform_ver = 0;
     dms_cxt->SSReformInfo.reform_ver_startup_wait = 0;
+    dms_cxt->SSReformInfo.switchover_demote_failure_signal_handled = false;
     dms_cxt->SSClusterState = NODESTATE_NORMAL;
     dms_cxt->SSRecoveryInfo.recovery_inst_id = INVALID_INSTANCEID;
     dms_cxt->SSRecoveryInfo.cluster_ondemand_status = CLUSTER_NORMAL;
diff --git a/src/include/ddes/dms/ss_dms_recovery.h b/src/include/ddes/dms/ss_dms_recovery.h
index f208b0116..b700340ce 100644
--- a/src/include/ddes/dms/ss_dms_recovery.h
+++ b/src/include/ddes/dms/ss_dms_recovery.h
@@ -88,6 +88,7 @@ typedef struct st_reform_info {
     bool is_hashmap_constructed;
     TimestampTz reform_ver;
     TimestampTz reform_ver_startup_wait;
+    bool switchover_demote_failure_signal_handled;
 } ss_reform_info_t;
 
 typedef enum st_failover_ckpt_status {
diff --git a/src/include/storage/pmsignal.h b/src/include/storage/pmsignal.h
index 195af874f..6bad09513 100644
--- a/src/include/storage/pmsignal.h
+++ b/src/include/storage/pmsignal.h
@@ -57,6 +57,7 @@ typedef enum {
     PMSIGNAL_DMS_REFORM,               /* dms reform start during PM_RUN */
     PMSIGNAL_DMS_REFORM_DONE,          /* dms reform done */
     PMSIGNAL_DMS_TERM_STARTUP,         /* term startup thread*/
+    PMSIGNAL_DMS_SWITCHOVER_DEMOTE_FAILURE_CHECK, /* figure out why switchover demote failed */
     NUM_PMSIGNALS                      /* Must be last value of enum! */
 } PMSignalReason;