Possible Duplicate:
How to get the current OS version of Windows Phone?
How to get installed OS version number on the Windows Phone 7?
You can use :
Environment.OSVersion.Version
System.Environment.OSVersion should do the trick: http://msdn.microsoft.com/en-us/library/system.environment.osversion.aspx
来源：https://stackoverflow.com/questions/8242032/how-to-get-os-version-number