Light Emitting Diode is a kind of semiconductor device, which was used as indicator light and display panel at first. With the appearance of the White Light-Emitting Diodes, the LED also developed to be used for lighting. It is a new type of light source in the 21st century with advantages of high efficiency, long-life span and invulnerability which can not be compared with the traditional light sources. When being pressured with positive voltage, the LED can emit single-color, discontinuous light, which belongs to a kind of Organic Electroluminescent Effect. Varying the chemic component of the semiconductor material being used, we can make the LED emit a certain light which is very closed to ultraviolet radiation, visible light and infrared ray