diff --git a/scripts/run-tsbs.sh b/scripts/run-tsbs.sh
index c2952b7578..ab352c1e57 100755
--- a/scripts/run-tsbs.sh
+++ b/scripts/run-tsbs.sh
@@ -17,7 +17,7 @@ export LOG_DIR=${LOG_DIR:-${CURR_DIR}/logs}
 export CERESDB_ADDR=${CERESDB_ADDR:-127.0.0.1:8831}
 export CERESDB_PID_FILE=${CURR_DIR}/ceresdb-server.pid
 export WRITE_WORKER_NUM=${WRITE_WORKER_NUM:-36}
-export WRITE_BATCH_SIZE=${WRITE_BATCH_SIZE:500}
+export WRITE_BATCH_SIZE=${WRITE_BATCH_SIZE:-500}
 # Where generated data stored
 export DATA_FILE=${DATA_FILE:-data.out}
 # How many values in host tag