We have studied the design of automatic welding robot system for central slot,in trems of robot,twin-wire welding machine, high-precision positioner,program-controlled system and welding clamps as we have detailed recommend.and have discussed twin-wire welding to apply to central slot welding.And the process measure of the twin -wire welding for central slot and choosing welding parameters have been studied.It has excellent quality welding seam with high efficiency,high level of automation.