diff --git a/src/common/inc/tglobal.h b/src/common/inc/tglobal.h
index beeb4e8b243e21e33f4162b07ec218c40e4029f9..7535fd8563a79f021ca2e958e2b70b135d1d038f 100644
--- a/src/common/inc/tglobal.h
+++ b/src/common/inc/tglobal.h
@@ -108,8 +108,9 @@ extern int32_t tsQuorum;
 extern int8_t  tsUpdate;
 extern int8_t  tsCacheLastRow;
 
-//tsdb 
-extern bool tsdbForceKeepFile;
+//tsdb
+extern bool    tsdbForceKeepFile;
+extern int32_t tsdbWalFlushSize;
 
 // balance
 extern int8_t  tsEnableBalance;
diff --git a/src/common/src/tglobal.c b/src/common/src/tglobal.c
index 7d352a9dc1f0a9a97c7c1920f898fb286a01497f..8fc05fe465e7604a11b4710abf0c2cf6cfe57e52 100644
--- a/src/common/src/tglobal.c
+++ b/src/common/src/tglobal.c
@@ -155,7 +155,8 @@ int32_t tsTsdbMetaCompactRatio = TSDB_META_COMPACT_RATIO;
 
 // tsdb config 
 // For backward compatibility
-bool tsdbForceKeepFile = false;
+bool    tsdbForceKeepFile = false;
+int32_t tsdbWalFlushSize = TSDB_DEFAULT_WAL_FLUSH_SIZE;  // [0,10000000] MB
 
 // balance
 int8_t  tsEnableBalance = 1;
@@ -1651,6 +1652,17 @@ static void doInitGlobalConfig(void) {
   cfg.unitType = TAOS_CFG_UTYPE_NONE;
   taosInitConfigOption(cfg);
 
+  // flush vnode wal file if walSize >= walFlushSize and walSize >= cache*blocks*0.5
+  cfg.option = "walFlushSize";
+  cfg.ptr = &tsdbWalFlushSize;
+  cfg.valType = TAOS_CFG_VTYPE_INT32;
+  cfg.cfgType = TSDB_CFG_CTYPE_B_CONFIG | TSDB_CFG_CTYPE_B_SHOW | TSDB_CFG_CTYPE_B_CLIENT;
+  cfg.minValue = TSDB_MIN_WAL_FLUSH_SIZE;
+  cfg.maxValue = TSDB_MAX_WAL_FLUSH_SIZE;
+  cfg.ptrLength = 0;
+  cfg.unitType = TAOS_CFG_UTYPE_MB;
+  taosInitConfigOption(cfg);
+
 #ifdef TD_TSZ
   // lossy compress
   cfg.option = "lossyColumns";
diff --git a/src/inc/taosdef.h b/src/inc/taosdef.h
index d80caad88db865d83986e4c19d95603eadde9884..6e9782fbd1f5b0923196647b4f06c0dfd201dfff 100644
--- a/src/inc/taosdef.h
+++ b/src/inc/taosdef.h
@@ -278,6 +278,10 @@ do { \
 #define TSDB_MAX_TOTAL_BLOCKS           10000
 #define TSDB_DEFAULT_TOTAL_BLOCKS       6
 
+#define TSDB_MIN_WAL_FLUSH_SIZE         0
+#define TSDB_MAX_WAL_FLUSH_SIZE         10000000
+#define TSDB_DEFAULT_WAL_FLUSH_SIZE     1024 // 1024MB
+
 #define TSDB_MIN_TABLES                 4
 #define TSDB_MAX_TABLES                 10000000
 #define TSDB_DEFAULT_TABLES             1000000
diff --git a/src/util/inc/tconfig.h b/src/util/inc/tconfig.h
index 2ba4b964c04b0a1ca9f883cd619aae2b7fcbe1d7..3ba0031a07a83d7374b3f940cf51bf31478cfd38 100644
--- a/src/util/inc/tconfig.h
+++ b/src/util/inc/tconfig.h
@@ -20,7 +20,7 @@
 extern "C" {
 #endif
 
-#define TSDB_CFG_MAX_NUM    124
+#define TSDB_CFG_MAX_NUM    125
 #define TSDB_CFG_PRINT_LEN  23
 #define TSDB_CFG_OPTION_LEN 24
 #define TSDB_CFG_VALUE_LEN  41