The composite insulator can bear the effective use of the narrow corridor open pressure, and is suitable for the transmission of city network technology improvement, can reduce tower height, can save a lot of human, material and financial resources, because of its bending strength is strong, porcelain crossarm prone to low-level chain rupture accident, is the ideal porcelain products instead of the bear, small volume, light weight, shock, resistance to impulse is strong, do not need artificial cleaning, to guarantee safe operation.