Their efficiency and their power factor of conventional independent electrical discharge machining (EDM) pulse power supplies with the current-limiting-resistor circuit is so low that they do not meet the need of advanced EDM technologies. The design of highly efficient EDM pulse power supply based on switching circuit pulse width modulation current closed-loop principle has been initiated. It is composed of such three stages as a single-phase active power factor correction preregulator, a full-bridge phase shift resonant converter based on machining current closed-loop control and a pulse generator based on machining sequence control. Therefore, the efficiency of the new system is considerably increased to about 70%, its weight and size is decreased much. Its power factor is a great deal increased to about 0.95. Experiment results have demonstrated that the highly efficient EDM pulse power supply is capable of low electrode wear, high speed, stable machining.