Abstract: The copper and molybdenum content of a low grade porphyry Cu-Mo ore are 0.339% and 0.022%，respectively.Cu-Mo mixed concentrate which will endure separation of copper from molybdenum,with Cu grade and recovery of only 17.23% and 86.40%，and Mo grade and recovery of only 0.629% and 48.60% was obtained fristly through the closed-circuit process of one roughing，three cleaning and three scavenging at the grinding fineness of 60% passing 0.074 mm.Reagents optimization experiments were conducted at the grinding fineness of on-site process to improve the bulk flotation index.The results indicated that：the collector of Pj-053+transformer oil replaced by Pj-053+Jingjiang-molybdenum in the original process，Cu-Mo mixed concentrate with Cu grade and recovery of 18.89% and 92.50%，and Mo grade and recovery of 1.023% and 77.19% were obtained respectively.Compared with the on-site process，mixed concentrate of Cu and Mo grade increased 1.66 and 0.394 percentage points，Cu and Mo recovery increased 6.10 and 28.59 percentage points.Index was improved significantly.

Key words: Low grade porphyry Cu-Mo ore, Bulk flotation, Reagents optimization, Jingjian-molybdenum