Base on the principles of the LED package structure and the LED optical model, we use Tracepro to do the simulation of LED devices. By changing the parameters of LED model, such as the package structure, the size of reflective cup, the height of chip and the angle of the reflective bowl, etc. We simulate the light intensity distribution curve of LED in different structures and find different results. That is a bigger height, a lager angle and a smaller curvature will make a better condenser effect. Compare with measurement data which shows that intensity distribution abide by some laws. Those conclusions can be used in guiding the package structure design of LEDs.