Abstract: A low-grade porphyry type silver bearing copper molybdenum ore in Xizang contains 0.35% Cu, 0.018% Mo, 2.18 g/t Ag and 2.5% S. The copper mineral is mainly chalcopyrite, followed by chalcocite. The molybdenum mineral is mainly molybdenite, the sulfur mineral is mainly pyrite, and the silver bearing mineral is silver. Pyrite has excellent floatability. The process of "floatability of copper and molybdenum - enhanced copper separation - copper sulfur separation" is adopted, combined with the use of strong selective collector BK-345, to obtain copper molybdenum mixed concentrate in low alkali environment. Through enhanced copper separation, the recovery of copper metal is improved. According to the ore characteristics of fine particles of copper minerals, the copper sulfur mixed coarse concentrate is superfine ground to -20 μm. The flotation closed-circuit test finally obtained the copper molybdenum mixed concentrate containing 26.88% Cu, 1.65% Mo, 110.5 g/t Ag, 61.2% Cu recovery, 73.9% Mo recovery and 40% Ag recovery, and obtained copper concentrate 2 containing 19.07% Cu, 112.7 g/t Ag, 24.7% Cu recovery and 23.2% Ag recovery. The comprehensive copper concentrate contained 24.04% Cu, 1.17% Mo and 111.3 g/t Ag, 85.9% Cu recovery, 82.3% Mo recovery and 63.2% Ag recovery. In the process of "total sulfur flotation copper sulfur separation", the separation of copper, molybdenum and sulfur needs to be restrained by adding strong lime, molybdenite is also strongly restrained, and the molybdenum recovery is low, only 57.5%. Compared with the mixed flotation process, on the premise that the recovery rate of other metals is slightly improved, the grade of molybdenum metal in the equal floatable process is increased by 0.84 percentage points and the recovery rate of molybdenum is increased by 16.4 percentage points.