LED (light-emitting diode) has the characteristics of energy saving, environmental protection, long life, low voltage, short switching time, etc. it is widely used in lighting, display, backlight and many other fields. At present, it is developing in the direction of higher brightness, high color, high weather resistance and high luminous uniformity. LED industry chain can be divided into upstream, midstream and downstream, which are LED epitaxial chip, LED packaging and LED application. As a link between the preceding and the following in the LED industry chain, LED packaging plays an important role in the whole industry chain. LED is composed of chip, wire, bracket, conductive adhesive and packaging material, among which packaging material is one of the key factors affecting the performance and service life of LED. At present, due to the special requirements of light transmittance, the packaging materials are mainly used in the market, such as epoxy resin, silicone, polycarbonate, glass, polymethylacrylate and other high transparency materials. However, most of these materials are hard and inconvenient to process, so they are basically used for outer lens materials. The traditional LED epoxy resin packaging materials have many defects, such as large internal stress, poor heat resistance, easy aging and so on, which can not meet the requirements of the growing performance of LED packaging materials, and are gradually replaced by organic silicon materials or organic silicon modified materials. Organosilicon material is a kind of material with high UV resistance, high aging resistance and low stress, which is an ideal choice for LED packaging materials. The transmittance of silicone is directly proportional to the luminous intensity and efficiency of LED devices. The higher the transmittance, the better the luminous intensity and efficiency of LED devices. Due to the high refractive index of Gan chip (about 2.2), the refractive index of general silicone material is only 1.4, so improving the refractive index of silicone material can reduce the difference between the refractive index of Gan chip and that of chip, reduce the light loss caused by interface reflection and refraction, and enhance the optical efficiency of LED devices.