Abstract: According to 4×4 latin square design, four 2.5-3 years old Simmnental steers with average body weight of （420±20） kg and equipped with permanent ruminal cannulas were selected in the experiment. With DL-met-Cu as Cu source and mixed concentrates and air dried corn stalks as basal diet, the effects of adding Cu on different levels （0, 8, 16 and 24 mg/kg dry matter） in diet on the nutrient digestibility of steers were studied on 1.3 M nutrition level. The results showed that the digestibility of crude fat in the group of 8 mg/kg was best and had no significant difference （P〉0.05）,the digestibility of no-nitrogen extracts in the group of 16 mg/kg was extemely significantly higher than that of the controlled group （P〈0.01）. The digestibilities of OM, CP, CF, NDF and ADF in the group of 24 mg/ kg were best, in whch the digestibility of CP was extremely significantly higher than that of the controlled group （P〈0.01）.The addition of 24 mg/kg dry Cu in diet could significantly improve the nutrient digestibility of diet. It was suggested that with DL-met-Cu as Cu source, the diet should be added with 24 mg/kg Cu.