Provided is a composite insulator which comprises an epoxy resin glass fiber rod which is arranged in the center, an umbrella skirt sheath which wraps the epoxy resin glass fiber rod, a metal connecting piece which is arranged on the end part of the epoxy resin glass fiber rod, and a pressure equalizing ring which is connected with the metal connecting piece. The pressure equalizing ring is provided with a polygon clamping piece which is connected with the metal connecting piece. The composite insulator and the pressure equalizing ring are fixed so that a phenomenon that the pressure equalizing ring rotates is avoided.