Cnc cutting machine series adopts Gantry structure and rectangular pipe welded into box structure. On the premise of ensuring welding strength, discontinuous welding is adopted to reduce welding deformation between square pipes. After the welding is completed, the welding parts are annealed and shotpeened, the welding residual stress is released, and the whole machine body is protected from deformation for a long time, so the precision of the machine tool is increased, the operation is stable and the cutting quality is guaranteed.