Composite insulator is made of epoxy glass fiber rods mandrel and with silicone rubber insulators, consisting of basic epoxy glass fiber rods of high mechanical strength, for ordinary 1.6 a 2.0 times the strength of steel and high strength porcelain 3 a 5 times.The three-layer silicone rubber insulated umbrella skirt has good anti-pollution and flashover performance, and it will not produce cracks, damages, porcelain glaze shedding and other common ceramic insulators.Because the middle layer of silicone rubber insulated umbrella skirt diameter than the diameter of the upper and lower two layers of insulation umbrella skirt, _ and the insulation of the two layers of umbrella skirt won't form a continuous conductive film, also won't produce leakage current heating effect, so it is difficult to cause insulator flashover.