Laser welding is an efficient and precise welding method using high energy density laser beam as heat source. Laser welding is one of the important aspects of laser material processing technology application. In the 1970s, it was mainly used for welding thin-wall materials and low-speed welding. The welding process is heat conduction type, that is, laser radiation heats the surface of the workpiece, and the surface heat diffuses internally through thermal conduction. By controlling the width, energy, peak power and repetition frequency of the laser pulse, the workpiece is melted to form a specific melt pool. Because of its unique advantages, it has been successfully applied in the precision welding of micro and small parts.