With the continuous development of CNC technology, CNC machine tools run at the higher speed. Cutting force will be greater, which is bound to exacerbate the wear and tear of the machine tool guides. Therefore, new requirements of numerical control machine tool guide surface hardness are proposed. Using Laser surface heat treatment process to scan the guide surface of CNC Machine Tool, the guide can get high hardness hardened layer. After being casted iron HT300 was heat treated by the laser, the microstructure is homogeneous, very fine martensite. Its Surface hardness can get to HV832. The treatment enhances the surface abrasion resistance, scratch-resistant capacity.