Aiming at electrical equipment failures caused by graphite fibers approaching or adhering to the surface of insulators, an external insulation breakdown discharge test platform for extreme power faults is designed. The platform encompasses test objectives, test objects, test environment, test device design, and test process design. The discharge process of insulators under the influence of graphite fibers and the effects of different graphite fiber parameters on insulator discharge are analyzed. The relationship between various graphite fiber parameters and the withstand voltage of insulators is studied, providing suggestions and theoretical basis for the structural design and optimization of insulators.