diff --git a/python/paddle_fl/mpc/examples/mnist_demo/run_standalone.sh b/python/paddle_fl/mpc/examples/mnist_demo/run_standalone.sh
index 932d8cf6f4da9940fdf0d1099beaf12a03bf0791..df688403172f6dfd6e7111d55c0baf5b070a592e 100755
--- a/python/paddle_fl/mpc/examples/mnist_demo/run_standalone.sh
+++ b/python/paddle_fl/mpc/examples/mnist_demo/run_standalone.sh
@@ -64,12 +64,14 @@ $REDIS_BIN -h $SERVER -p $PORT flushall
 
 # remove temp data generated in last time
 PRED_FILE="/tmp/mnist_output_prediction.*"
-if [ "$PRED_FILE" ]; then
+ls ${PRED_FILE}
+if [ $? -eq 0 ]; then
         rm -rf $PRED_FILE
 fi
 
 TRAINING_FILE="/tmp/mnist2_feature.part*"
-if [ ! "$TRAINING_FILE" ]; then
+ls ${TRAINING_FILE}
+if [ $? -ne 0 ]; then
     echo "There is no data in /tmp, please prepare data with "python prepare.py" firstly"
     exit 1
 else