Composite bushing is a kind of equipment component often used in the circuit system in the building. Its main function is to protect the exposed wires in the circuit system. Due to the complexity of the circuit system in the building, the use of composite bushings has also increased with the increase in the number of buildings. Composite sleeves appear in the market in the eyes of users mainly in the form of medium prices, which is not too cheap but acceptable. However, for the safety of the circuit system and the family's personal property, most people still choose to buy it at a medium price, which is relatively safe and priceless. Although the quality of early domestic composite casing was not very high-end, its safety performance was still guaranteed, and the safety of people's lives and property cannot be ignored. With the development of science and technology in recent years, the technology of composite casing is also advancing by leaps and bounds, but the price is also advancing by leaps and bounds. From low prices, simple casing materials to complex molecular materials and not cheap prices. While the user's safety is guaranteed, the market is also supported by consumer economics. Although the price is expensive, the security performance is higher, which is still a good deal.