PET is a milky white or yellowish, highly crystalline polymer with a smooth, glossy surface. It has excellent physical and mechanical properties in a wide range of temperatures, up to 120℃, and excellent electrical insulation. Even at high temperature and high frequency, its electrical properties are still good, but it has poor corona resistance, creep resistance, fatigue resistance, friction resistance and dimensional stability. PET has ester bond, decomposition will occur under the action of strong acid, strong alkali and water steam, organic solvent resistance, good weather resistance. Disadvantages are slow crystallization rate, molding processing difficulties, high molding temperature, long production cycle, poor impact performance. Generally through strengthening, filling, blending and other methods to improve its workability and physical properties, with glass fiber reinforcement effect is obvious, improve resin rigidity, heat resistance, drug resistance, electrical performance and weather resistance. But still need to improve the shortcoming of slow crystallization speed, can be taken to add nucleating agent and crystallization accelerator and other means. Flame retardancy and self - flameout of PET can be improved by adding flame retardants and flame retardants.