Now i have imported one 3d model in my scene when i drag that model from project to hierarchy my system was rebooted. So i want to know the maximum count of tris and poly in one scenefor android and PC standalone).
There is none. Ram and Performance tells you about the limits at your current platform. There is the 65k limit for a single mesh. But besides that it`s totally up to the hardware and, very important, the rest of the scene too, that tells you about how much tris can be dealt with in a scene before the fps goes down to a crawl.
At Android you may hit other limits. Like a maximum texture size of 1024x1024.
I found Unity to be very unstable on my first graphics card, which was a Gigabyte 5870… I couldnt spend longer than 5 minutes using it before the video card drivers would start freezing.
I suspect you may be experiencing a similar problem.