Laser welding can be implemented using continuous or pulsed laser beam, laser welding principle can be divided into heat-conduction welding and deep penetration laser welding. Power density is less than the 104~105 W/cm2 for the heat conduction welding, fusion welding depth, slow; power density is greater than 105~107 when W/cm2, concave metal surface under the action of heat into "the void", forming welding, welding speed, the ratio of depth to width feature.