Abstract: Stud plunge speed is one of the important parameters in arc stud welding.Through the analysis of operating principle of electromagnetic welding gun which was widely employed in engineering,it was proposed that stud welding procedure could be realized even with a slower plunge speed,however an adequate extrusion force was needed simultaneously.An arc stud welding gun based on stepping motor and its control system were developed to accomplish the slow plunge arc stud welding.A stepping motor was taken as actuating unit and screw-driven device as moving unit,to furnish the adequate extrusion force for melted metal during the course of the slow plunge.It was indicated from test results that the stepping arc stud welding gun could realize the welding process of slow stud plunge.Further more,the result of bend test proved that the joint was fit for service.