A new method of ultrasomic vibration alectrical discharge machining (UEDM) in gas is proposed in this paper, it is shown that alectlical discharge machining (EDM) with ultrasolfic aid can be achieved well in a gas medimn. The tool electrode is formed into a tbin walled pipe, mid a high pressme gas medimn is supplied through it. During machining, ultrasonic vibration of the workpiece cml improve the machinring process. Molten workpiece material can be ejected from the base body of the workpiece with the aid of ultrasolfic vibration mul be removed/flushed out of the working gap without becoming reattached to the alectrode. Selecting #45 steel and copper as the workpiece material and alectrode material, respectively, experiments have been cm-ried out, the results showing that UEDM is a method with a high material removal rate (MRR). The greatest adwntages of this technique are lower pollution and a low electrode wear ratio.