Abstract: This paper analyzes the technology characteristics of stainless steel plasma arc-gas tungsten arc double-sided arc welding process,which could increase penetration and reduce distortion,then this process is applicable to weld the thick plate.After the keyhole was established,the arcs during the double-sided arc welding are apparently constricted to some extent,and the arc voltage between the two welding torches descends,which can economize on energy.Because the arc heats the workpiece within the weld pool after penetrating,the arc thermal efficiency was improved.The surface tension,arc blow force and electromagnetic force work positive to improve the penetration,and the buoyancy can increase the width in the middle of weld pool.