This paper describes a new method of die surface modification by ordinary Electrical Discharge Machining (EDM) tool. First, the principle of this method is studied. Secondly, the reason for appearance of cracks on the surface of coating layer in the electrical discharge coating with conventional pulse power supply are analyzed. At last, the new type special pulse power supply with additional pulse current is designed. Scenix single-chip is selected as pulse generator, which runs the fastest among all single-chips. The corresponding program can make the pulse power supply produce the additional pulse current. At the same time, the special pulse power supply can communicate different machining parameters with industrial personal computer by serial port of PIC single-chip according to the coating requires, and then PIC single-chip convey machining parameters to Scenix single-chip by the communication interface. Through process experiment, the special pulse power supply for electrical discharge coating behaves well, and the compacted coating layer without cracks deposited on the surface of die by EDM can be obtained, which can prolong the life of die.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.