diff --git a/tools/gen_ota_zip.py b/tools/gen_ota_zip.py
index 4fbffe0..519112e 100755
--- a/tools/gen_ota_zip.py
+++ b/tools/gen_ota_zip.py
@@ -99,15 +99,15 @@ def gen_diff_ota_sh(patch_path, bin_list, newpartition_list, args, tmp_folder):
 
     ota_progress = 30.0
     max_progress = 100 - args.user_end_script_progress
+    gen_progress = (max_progress - ota_progress) * float(sum(bin_size_list[:bin_list_cnt]) / sum (bin_size_list))
     ota_progress_list = []
 
     for i in range(bin_list_cnt):
-        ota_progress += float(patch_size_list[i] / sum(patch_size_list)) * (max_progress - 30)
-        ota_progress_list.append(math.floor(ota_progress))
+        ota_progress_list.insert(len(ota_progress_list) // 2, math.floor(ota_progress + float(sum(patch_size_list[:i + 1]) / sum(patch_size_list)) * gen_progress * 0.1))
+        ota_progress_list.append(math.floor(ota_progress + gen_progress * 0.1 + float(sum(patch_size_list[:i + 1]) / sum(patch_size_list)) * gen_progress * 0.9))
 
     for j in range(len(newpartition_list)):
-        ota_progress += float(bin_size_list[i + j] / sum(bin_size_list)) * (max_progress - 70)
-        ota_progress_list.append(math.floor(ota_progress))
+        ota_progress_list.append(math.floor(ota_progress + gen_progress + float(sum(bin_size_list[bin_list_cnt:bin_list_cnt + j + 1]) / sum(bin_size_list[bin_list_cnt:])) * (max_progress - ota_progress - gen_progress)))
 
     ota_progress_list[-1] = max_progress
     str = \
@@ -117,39 +117,28 @@ def gen_diff_ota_sh(patch_path, bin_list, newpartition_list, args, tmp_folder):
 ''' % (ota_progress_list[0])
     fd.write(str)
 
-    str = \
-'''if [ ! -e /ota/%s ]
-then
-''' % (bin_list[bin_list_cnt - 1])
-    fd.write(str)
-
-    for i in range(bin_list_cnt):
+    bin_list_cnt *= 2
+    for i, j in zip(list(range(bin_list_cnt // 2)) * 2, range(bin_list_cnt)):
         str = \
 '''
-    echo "generate %s"%s
-    time "ddelta_apply %s %s/ /ota/%spatch"
-    if [ $? -ne 0 ]
-    then
-        echo "ddelta_apply %s failed"%s
-        setprop ota.progress.current -1
-        exit
-    fi
-
-    setprop ota.progress.current %d
+echo "generate %s"%s
+time "ddelta_apply %s %s/ /ota/%spatch %s"
+if [ $? -ne 0 ]
+then
+    echo "ddelta_apply %s failed"%s
+    setprop ota.progress.current -1
+    reboot
+fi
+
+setprop ota.progress.current %d
 ''' % (bin_list[i], args.otalog,
-       patch_path[i], args.ota_tmp, bin_list[i][:-3],
+       patch_path[i], args.ota_tmp, bin_list[i][:-3], "precheck" if j < bin_list_cnt // 2 else "",
        bin_list[i][:-4], args.otalog,
-       ota_progress_list[i])
-        if i + 1 < bin_list_cnt:
-            str += '    setprop ota.progress.next %d\n' % (ota_progress_list[i + 1])
+       ota_progress_list[j])
+        if j + 1 < bin_list_cnt:
+            str += 'setprop ota.progress.next %d\n' % (ota_progress_list[j + 1])
         fd.write(str)
 
-    str = \
-'''
-fi
-'''
-    fd.write(str)
-
     i = 0
     for file in newpartition_list:
         str = \