In view of the abnormal discharge phenomena such as short circuit,partial discharge and secondary discharge caused by particle bridge between electrode and workpiece because of poor chip removal in common short arc machining,a new method of ultrasonic vibration assisted short arc machining was proposed to improve the machining quality of workpiece.The macroscopic characteristics and microscopic morphology of the workpiece after common short arc and composite machining were compared by experiments.The surface morphology,roughness and energy spectrum of the machined surface were measured and analyzed by ultra-depth microscope and electron scanning microscope.The results show that:after the coupling of the two special processing technologies,the surface topography of the workpiece has changed,the surface texture is disordered and homogenized under the action of ultrasonic,the number of electric pitting and surface micro-cracks are significantly reduced,the thickness of the recast layer is reduced from 93.06 μm to 25.39 μm under deep milling,the surface roughness is reduced by more than 16%,and the surface elements of the material are modified.This provides a new way for short arc technology to improve machining quality,material modification and technology coupling development.