Abstract: Conventional electrical discharge machining(EDM) is generally carried out in dielectric liquid such as kerosene-based oil. Although liquid medium is regarded as indispensable for the stability and efficiency of the process，but it may cause certain environmental pollution. Based on analyzing the machining mechanism of EDM in compressed gas，a new wire-cut EDM(WEDM) in gas is presented. For WEDM in gas，its traveling tool electrode may conduce to removing debris from the working gap even in atmosphere and by utilizing this proc-ess as finish-cut，obtained straightness along the work's thick-ness direction is significantly better than that machined in water. Experimental results of low speed WEDM have proved above-mentioned features and those of high speed WEDM preliminarily show that WEDM in gas has broad prospects to its application.

Key words: Multiple-cut (finish-cut, Straightness, WEDM in gas