An optimization method of laser quenching process parameters of Cr12MoV die steel is proposed based on the orthogonal experiment and Vague set. The laser power, scanning speed, overlap rate, black paint thickness are taken as optimizing process parameters, while the quenching layer surface hardness after quenching, quenching layer depth, relative wear rate and corrosion rate of quenching layer are taken as integrated process optimization objectives. Orthogonal experiment is first carried out to obtain the data samples, and then the data are analyzed and processed by the Vague set theory to realize the optimization of process parameters. The optimization of single process is first carried out, and then comprehensive process optimization is taken through single process objective weight sum, where the multi-objective optimization problem is transformed into a single objective optimization problem. The optimization results are listed as laser power of 1400 kW, scanning speed of 15 mm/s, lap ratio of 40%, and coating thickness of 60 μm. Test experimental results indicate that the optimization of process parameters make the hardness of quenching layer increase by 1.62%, the relative abrasion value decrease by 9.84%, the corrosion rate decrease by 9.26%, and the quenching layer depth only decrease by 1.33%.