Now I change:
media_root = os.path.normpath(settings.MEDIA_ROOT)
if path.startswith(media_root):
path = path[len(media_root):]
if path[0] == '/':
path = path[1:]
to:
media_root = os.path.normpath(settings.MEDIA_ROOT)
if path.startswith(media_root.lower()):
path = path[len(media_root)+1:]
if path[0] == '/':
path = path[1:]
it is work find