You haven't given much to go on but here are some things to check right off the bat:
- If the application isn't signed, and you don't have a debug token, or the token has expired or development mode has expired on the device the application will exit from the splash screen.
- If you aren't requesting all necessary permissions in you app-descriptor.xml file your application may be getting unexpected results that cause the crash.
- If you have a higher OS version on the simulator than the device, you may be using QML that isn't recognized by the device QML compiler which will cause a crash when the returned QML document is null. This is usually logged to the console.
If it isn't one of those, use the IDE run the application on the device and see if there is anything useful logged to the console. If not, set the IDE into debug mode to run the program under the debugger on the device. It will halt execution where the application is aborting. This may be deep in a system library but you may be able to step up the call stack to your code to find out the location of the problem.