HW120-P is a high-efficient and precise product for high-power laser composite welding of thick plates, which is a new welding method combining the two processes of laser welding and electric arc welding. The two heat sources act on the plates at the same time, the laser can improve the stability of the arc, and the arc can attract the photo-plasma to promote the absorption of the laser by the material, which is especially suitable for welding thick plates by combining the advantages of laser welding and arc welding, and can play the effect of 1+1＞2. It is especially suitable for welding thick plates, and can bring out the effect of 1+1＞2.