In order to determine the heat source of short electric arc machining (SEAM),the Gaussian heat source and even heat source were selected,and the threedimensional short arc single pit finite elements simulation models under two heat sources were established with Ti-6Al-4V as the workpiece material.A single pulse experiment was carried out,the collected voltage and current waveforms were analyzed,the photos taken by the high-speed camera were watched,the single pit size,three-dimensional shape and contour curve taken by ultra-view deep microscope were compared.It is concluded that Gaussian heat source is more suitable for SEAM processing.A 2D section of the 3D pit was taken on the basis of determining the heat source.It is proved that the built Gaussian heat source is reliable.It can be used to accurately simulate the forming of the discharge pit of short electric arc machining.