LED (Light Emitting Diode) has the characteristics of energy saving, environmental protection, long life, low use voltage, short switching time, etc. It is widely used in many fields such as lighting, display, backlight and so on. At present, it is developing in the direction of higher brightness, high color, high weather resistance, and high light emission uniformity. The LED industry chain can be divided into upper, middle and lower reaches, which are LED epitaxial chips, LED packages and LED applications. As an integrated LED package in the LED industry chain, it plays an important role in the entire industry chain. LEDs are composed of chips, wires, brackets, conductive glue, packaging materials, etc. Among them, packaging materials are one of the key factors affecting LED performance and service life. At present, due to its special requirements for light transmission, packaging materials currently used in the market are mainly high transparency materials such as epoxy resin, silicone, polycarbonate, glass, and polymethacrylate. However, since most of these materials are relatively hard and inconvenient to process, they are basically used for outer lens materials. Traditional LED epoxy resin packaging materials have defects such as large internal stress, poor heat resistance, and easy ageing, and cannot meet the growing needs of LED packaging materials. They are gradually being replaced by silicone materials or silicone modified materials. Silicone material is a material with high UV resistance, high aging resistance and low stress, making it an ideal choice for LED packaging materials. The light transmittance of silicone resin is directly proportional to the light emitting intensity and efficiency of the LED device. The higher the light transmittance, it is beneficial to increase the light emitting intensity and efficiency of the LED device. Because the gallium nitride chip has a high refractive index (about 2.2), the refractive index of general silicone materials is only 1.4, so increasing the refractive index of silicone materials can reduce the difference with the refractive index of the chip, reducing the interface reflection and refractive band. Incoming light loss enhances the light extraction efficiency of the LED device.