Abstract: In order to manufacture deep microslit,a new micro EDM process was developed.With this method a raw rod electrode with negative polarity is used to scan a metal plate to form a through slit.Then the rod electrode is moved perpendicularly to the slit,with certain distance from the center of the slit.Micro flat electrode is obtained after the raw rod electrode is fed into the plate in the axial direction of the rod.Micro slips are achieved by scan machining with the micro flat electrode finally.At last deep micro-slits with aspect ratio of 18:1 and of parallel and equal width have been successfully achieved.Compared to the methods of reverse-EDM with block electrode and WEDG,the self-manufacturing method of flat electrode is adopted to avoid the requirement for precision positioning between the electrodes.To manufacture micro slit on metal part,micro-EDM using flat electrode is suggested,which may have less electrode wear and higher efficiency than that of using rod electrode.