Surface treatment process of mould

The invention belongs to the technical field of moulds and in particular relates to a surface treatment process of a mould. The surface treatment process comprises the following steps: selecting steel with the mass percent of more than 0.5% for making the mould, and polishing the surface of the mould to guarantee that the roughness Ra of the surface of the mould is less than 0.2 micron; degreasing the polished mould; preparing a salt bath; heating the treated mould to a constant temperature in the salt bath so as to form a coverage layer on the surface of the mould; quenching and washing to finish the treatment process. Compared with the prior art, the surface treatment process has the characteristics that the dense and uniform coverage layer can be formed on the surface of the mould and has performances such as very high hardness (HV3,200), very high wear resistance, occlusion resistance and corrosion resistance, the service life of the mould can be greatly prolonged (by multiple to tens of times), the repai