my game is running damn slowly in android device?

I have created an android game, it is working well in my system but when i taking built in android device it struck and when play it runs damn slow even its taking too much time to load.I dont know whats the problem, may be problem in my rendering procedure. my built size is only 14 mb.Please anyone help me in solving this problem.

A desktop PC has a much better graphics card than any mobile device. If you’ve been working on if for a while and only testing on the desktop PC, it may be that you’ve just made something that won’t run on an Android and you’re going to have to go back to the drawing board, and test constantly on the target hardware the next time.

Your question is very broad and you gave no information that would help someone diagnose your problem.
At least post a screenshot.
How many draw calls are you getting (click “Stats” button over the game view.) How many materials do you have in the scene? How many lights? Are you using real-time shadows? Built-in terrain with plants and trees?

For the record, the simple answer is “Use the profiler…”. A major and amazing feature of Unity!