Question: I am developing the smart device application. There are different screen resolution for different window mobile devices. I want to know that which is the standard screen resolution for windows mobile?

Answer: 
There is no standard.

Many possibilities exist and the recent devices usually have 800x480. Others have: 640x480, 320x240, 320x320, 400x240, etc.
The default controls scale pretty well across resolutions. I've created forms in Visual Studio and deployed to multiple resolutions without any modifications.