The microstructure and wearing resistance of 5CrMnMo hot working die steel with four different amounts of additions of Ce was studied and compared with that without Ce by analyzing the microstructure, worn-out appearance, average wearing rate and friction coefficient. The results showed that when the addition of Ce was proper, the microstructure was significantly refined, the average wearing rate and friction coefficient were reduced markedly and the grinding crack image was also relatively thin and shallow. Therefore, the wear resistance was improved effectively. When the addition of Ce is 0.20 %( mass percent), 5CrMnMo steel had the least surface average wearing quantities and the best wearing resistance. As compared with the 5CrMnMo steel without Ce, the average wearing rate decreasing margin of that with 0.20% Ce was high to 36.19%.