Abstract: In the case study of the mixed concentrates produced in a porphyry copper-molybdenum mine from Inner Mongolia,the small-scale closed-circuit flotation test and the MPP continuous pilot flotation test for copper and molybdenum separation are carried out by using the composite reagents combining sulfhydryl new type copper and molybdenum separation inhibitors CG4039,CG4006,and NaHS.The results show when the total dosage of the inhibitor is 20.80 kg/t,the molybdenum grade of the molybdenum concentrate obtained by the small-scale closed-circuit flotation test is 53.24 % and the molybdenum recovery rate is 90.86 %;under the same conditions,the molybdenum concentrate obtained by the MPP continuous pilot flotation test has the molybdenum grade of 48.92 % and molybdenum recovery rate of 87.92 %.The molybdenum grade of the copper concentrate is 0.41 %.The copper and molybdenum separation outcome is good and the index is better compared to that on the field.