Abstract: The microstructure and hardness of Cr12W steel with optical microscopy and hardness tester were analyzed. The influence on microstructure and hardness of different annealing process, quenching and tempering process were studied.The results indicate that after annealing at 860℃, uniform and spherordizing microstructure can be obtained and hardness is 240 HBW. With the increase of quenching temperature, the amount of carbides is decreasing. Cr12W has fine microstructures after quenching at 960-980℃ and reaches maximum hardness at 970℃.Punching die is used with high hardness, so low temperature tempering is chose,and the hardness reaches 60 HRC after tempering at 200℃.The tempering stability and impact toughness of Cr12W steel is better than Cr12 steel,and the microstructure is finer.