Laser lab melt-in welding technology and production line of multi-commercial vehicle’s roof and side body adopt fiber laser source to weld left and right sides roof with dual light path output system. It adopts laser welding head with pinch roller to solve the light line problems of long route, curve and multi-section welding kerf. It adopts high intelligent welding kerf search&positioning&tracking system to solve the positioning problems of long route, curve and multi-section welding kerf. In addition, it adopts 6+1-axis robot to solve welding problems of long route.Zoom Lebron Soldiers IX 9