The invention relates to a high-voltage signal generator which comprises the components of a high-voltage source, an electric discharging device and a capacitive wiring conversion device. The capacitive wiring conversion device comprises a base board, a capacitive wiring board and a capacitive wiring conversion mechanism, wherein the capacitive wiring board and the capacitive wiring conversion mechanism are arranged above the base board. The capacitive wiring conversion mechanism comprises a serial wiring module, a parallel wiring module and a serial-parallel wiring module. The electric discharging device comprises a swing rod charging/discharging mechanism and a driving mechanism which drives the swing rod charging/discharging mechanism to swing. The swing rod charging/discharging mechanism comprises an anode swing rod, a cathode swing rod, a charging wiring board and an insulating baffle board. The insulating baffle board is arranged between the anode swing rod and the cathode swing rod. The invention further relates to a method for performing cable fault testing through the high-voltage signal generator. Compared with the prior art, the high-voltage signal generator is advantageous in that a charging operation is totally separated from a discharging operation in the charging process and the discharging process; the charging process and the discharging process are individually performed; a cross influence is prevented; and high operation stability of the whole equipment is ensured.