diff --git a/data/scripts/COCO.sh b/data/scripts/COCO.sh
index 799cb135f..95a34e146 100644
--- a/data/scripts/COCO.sh
+++ b/data/scripts/COCO.sh
@@ -1,6 +1,10 @@
 #!/bin/bash
 
 start=`date +%s`
+trainfile="train2017.zip"
+valfile="val2017.zip"
+annotations_trainval2014="annotations_trainval2014.zip"
+annotations_trainval2017="annotations_trainval2017.zip"
 
 # handle optional download dir
 if [ -z "$1" ]
@@ -30,10 +34,23 @@ fi
 
 # Download the image data.
 cd ./images
-echo "Downloading MSCOCO train images ..."
-curl -LO http://images.cocodataset.org/zips/train2017.zip
-echo "Downloading MSCOCO val images ..."
-curl -LO http://images.cocodataset.org/zips/val2017.zip
+# check train2017.zip exist
+if [ ! -f "$trainfile" ]
+  then
+  echo "Downloading MSCOCO train images ..."
+  curl -LO http://images.cocodataset.org/zips/train2017.zip
+  else
+  echo "train2017.zip exist"
+fi
+
+# check val2017.zip exist
+if [ ! -f "$valfile" ]
+  then
+  echo "Downloading MSCOCO val images ..."
+  curl -LO http://images.cocodataset.org/zips/val2017.zip
+  else
+  echo "val2017.zip exist"
+fi
 
 cd ../
 if [ ! -d annotations ]
@@ -43,27 +60,49 @@ fi
 
 # Download the annotation data.
 cd ./annotations
-echo "Downloading MSCOCO train/val annotations ..."
-curl -LO http://images.cocodataset.org/annotations/annotations_trainval2014.zip
-curl -LO http://images.cocodataset.org/annotations/annotations_trainval2017.zip
+
+if [ ! -f "$annotations_trainval2014" ] || [ ! -f "$annotations_trainval2017" ]; then
+    echo "Downloading MSCOCO train/val annotations ..."
+
+    if [ ! -f "$annotations_trainval2014" ]; then
+        echo "$annotations_trainval2014 not exist, now downloading ..."
+        curl -LO http://images.cocodataset.org/annotations/annotations_trainval2014.zip
+    fi
+
+    if [ ! -f "$annotations_trainval2017" ]; then
+        echo "$annotations_trainval2017 not exist, now downloading..."
+        curl -LO http://images.cocodataset.org/annotations/annotations_trainval2017.zip
+    fi
+else
+    echo "annotations exist"
+fi
+
 echo "Finished downloading. Now extracting ..."
 
 # Unzip data
+if ls ../images/*.jpg 1> /dev/null 2>&1; then
+  echo "jpg files exist, starting deletion..."
+  rm ../images/*.jpg
+fi
 echo "Extracting train images ..."
 unzip -qqjd ../images ../images/train2017.zip
 echo "Extracting val images ..."
 unzip -qqjd ../images ../images/val2017.zip
+
+if ls ./annotations/*.json 1> /dev/null 2>&1; then
+  echo "json files exist, starting deletion..."
+  rm ./annotations/*.json
+fi
 echo "Extracting annotations ..."
 unzip -qqd .. ./annotations_trainval2014.zip
 unzip -qqd .. ./annotations_trainval2017.zip
 
-echo "Removing zip files ..."
+echo "Download completed, Removing zip files ..."
 rm ../images/train2017.zip
 rm ../images/val2017.zip
 rm ./annotations_trainval2014.zip
 rm ./annotations_trainval2017.zip
 
-
 end=`date +%s`
 runtime=$((end-start))