Abstract: In order to improve the hardness and wear resistance of Cr12MoV surface, CrAlSiN coating was prepared on the surface of Cr12MoV cold working die steel after quenching and nitriding by multi-arc ion plating technology. The results show that the microhardness of Cr12MoV steel after quenching, nitriding and coating treatment significantly improves, and the hardness of coating film after quenching is 3028HV, and the hardness of the coating after nitriding is 3471 HV, which is more than 12 times of the hardness of substrate (283HV). The friction coefficient of the coating after nitriding treatment is lower than that after quenching. The comprehensive comparison of hardness, wear resistance and friction coefficient of each sample shows that the effect of nitriding treatment is better than that of quenching treatment before multi-arc ion plating CrAlSiN coating.