diff --git a/src/gausskernel/process/postmaster/checkpointer.cpp b/src/gausskernel/process/postmaster/checkpointer.cpp
index 83038ff39..52a0e9142 100755
--- a/src/gausskernel/process/postmaster/checkpointer.cpp
+++ b/src/gausskernel/process/postmaster/checkpointer.cpp
@@ -387,7 +387,6 @@ void CheckpointerMain(void)
             u_sess->attr.attr_storage.CheckPointTimeout = ENABLE_INCRE_CKPT
                                                               ? u_sess->attr.attr_storage.incrCheckPointTimeout
                                                               : u_sess->attr.attr_storage.fullCheckPointTimeout;
-            most_available_sync = (volatile bool) u_sess->attr.attr_storage.guc_most_available_sync;
 
             /*
              * Checkpointer is the last process to shut down, so we ask it to
@@ -715,7 +714,6 @@ void CheckpointWriteDelay(int flags, double progress)
         if (t_thrd.checkpoint_cxt.got_SIGHUP) {
             t_thrd.checkpoint_cxt.got_SIGHUP = false;
             ProcessConfigFile(PGC_SIGHUP);
-            most_available_sync = (volatile bool)u_sess->attr.attr_storage.guc_most_available_sync;
             /* update shmem copies of config variables */
             UpdateSharedMemoryConfig();
         }
diff --git a/src/gausskernel/process/tcop/postgres.cpp b/src/gausskernel/process/tcop/postgres.cpp
index 12f8b1493..56b203ab9 100755
--- a/src/gausskernel/process/tcop/postgres.cpp
+++ b/src/gausskernel/process/tcop/postgres.cpp
@@ -82,6 +82,7 @@
 #include "replication/datasender.h"
 #include "replication/walsender.h"
 #include "replication/slot.h"
+#include "replication/syncrep.h"
 #include "rewrite/rewriteHandler.h"
 #include "storage/buf/bufmgr.h"
 #include "storage/ipc.h"
@@ -6940,6 +6941,8 @@ void reload_configfile(void)
         }
         u_sess->sig_cxt.got_SIGHUP = false;
         ProcessConfigFile(PGC_SIGHUP);
+        most_available_sync = (volatile bool) u_sess->attr.attr_storage.guc_most_available_sync;
+        SyncRepUpdateSyncStandbysDefined();
         if (currentOwner == NULL) {
             ResourceOwnerRelease(t_thrd.utils_cxt.CurrentResourceOwner, RESOURCE_RELEASE_BEFORE_LOCKS, true, true);
             ResourceOwnerRelease(t_thrd.utils_cxt.CurrentResourceOwner, RESOURCE_RELEASE_LOCKS, true, true);
diff --git a/src/gausskernel/process/threadpool/threadpool_scheduler.cpp b/src/gausskernel/process/threadpool/threadpool_scheduler.cpp
index 7523dfa85..84ed7196e 100644
--- a/src/gausskernel/process/threadpool/threadpool_scheduler.cpp
+++ b/src/gausskernel/process/threadpool/threadpool_scheduler.cpp
@@ -40,6 +40,7 @@
 #include "utils/memutils.h"
 #include "utils/ps_status.h"
 #include "utils/guc.h"
+#include "replication/syncrep.h"
 
 #define SCHEDULER_TIME_UNIT 1000000  //us
 #define ENLARGE_THREAD_TIME 5
@@ -63,6 +64,9 @@ static void reloadConfigFileIfNecessary()
     if (t_thrd.threadpool_cxt.scheduler->m_getSIGHUP) {
         t_thrd.threadpool_cxt.scheduler->m_getSIGHUP = false;
         ProcessConfigFile(PGC_SIGHUP);
+        /* Update most_available_sync if it's modified dynamically. */
+        most_available_sync = (volatile bool) u_sess->attr.attr_storage.guc_most_available_sync;
+        SyncRepUpdateSyncStandbysDefined();
     }
 }
 
diff --git a/src/gausskernel/storage/replication/syncrep.cpp b/src/gausskernel/storage/replication/syncrep.cpp
index 147ee4498..87f6494c0 100755
--- a/src/gausskernel/storage/replication/syncrep.cpp
+++ b/src/gausskernel/storage/replication/syncrep.cpp
@@ -313,8 +313,11 @@ void SyncRepWaitForLSN(XLogRecPtr XactCommitLSN, bool enableHandleCancel)
         }
 
         /*
-         * If we  modify the syncmode dynamically, we'll stop wait
+         * If we modify the syncmode dynamically, we'll stop wait.
+         * Reload config file here to update most_available_sync if it's modified
+         * dynamically.
          */
+        reload_configfile();
         if ((t_thrd.walsender_cxt.WalSndCtl->sync_master_standalone && !IS_SHARED_STORAGE_MODE &&
              !DelayIntoMostAvaSync(false)) ||
             u_sess->attr.attr_storage.guc_synchronous_commit <= SYNCHRONOUS_COMMIT_LOCAL_FLUSH) {