Abstract: A copper and molybdenum mine in Inner Mongolia belongs to a low-grade large-scale porphyry copper-molybdenite mine, and main useful minerals of the ore are chalcopyrite, bornite, chalcocite, cyanite and molybdenite.The copper-molybdenum mixed priority (for pyrite) process is adopted in the recovery of copper and molybdenum in the field industrial production, and the process is relatively simple. With the continuous change of ore properties, the adaptability of the original reagent system to the existing ore has become worse.The recovery of copper and molybdenum has decreased in different degrees at present, especially the molybdenum recovery has decreased significantly, and the molybdenum recovery fluctuates between 30% and 60%. In order to improve the recovery of copper and molybdenum, the optimization test of the reagent system was carried out. After the optimization of the reagent system, the collector BK925 is used instead of the original collector, which can realize the efficient recovery of copper molybdenum, and the recovery of copper molybdenum was over 87%.