It makes use of high energy laser beam focusing on a fixed point to weld workpiece immediately. The tension strength is more than 5 kgf/cm2 on each welding point. To match different requirement of structure strength, number of welding points can be adjusted accordingly. Welding point is very small to notice, that's why it is perfect for inner or outer mechanic parts of metal thin plate. Laser welding is directly implemented on the workpiece. Design complexation can be effectively reduced.