Stream VOD with thumbnail

How can i streaming vod with thumbnail ?

Nimble has no functionality to generate thumbnails, you can use FFmpeg command like this to generate it:
ffmpeg -i video.mp4 -ss 00:00:30 -vframes 1 -vf scale=320:-1 thumb.jpg

You can also read this discussion for thumbnails generation with ffmpeg:
http://superuser.com/questions/538112/meaningful-thumbnails-for-a-video-using-ffmpeg

thank for your reply
and then how to streaming nimble with vod have thumbnail, can we use smil ??

I don't understand how thumbnail is related to smil, could you explain your use case?

ex: http://118.69.166.182/vod/chayngaydi/chayngaydi-720.mp4/playlist.m3u8
==> how can play this video with image thumbnail ?
i stream this video with nimble streaming

You want to display thumbnails on time scale, right?
It's not related to smil anyway, here is description for JW Player: https://support.jwplayer.com/articles/how-to-add-preview-thumbnails
You must prepare thumbnails and then create WEBVTT file that contain match between time and thumbnails. Then on player page you should pass it to jwplayer setup like this:
{ file: "<video_url>",
tracks: [{file:"http://<nimble_ip>/vod/thumbs.webvtt", kind: "thumbnails"}]
}