Abstract: The composition of a low-grade porphyry copper-molybdenum ore mineral in Inner Mongolia is complex，and the valuable minerals are mutually embedded in raw and unevenly grain size In order to utilize the minerals，beneficiation tests on the ore are made by adopting the process of stage grinding and stage bulk flotation The results showed that copper-molybdenum mixed concentrate with Cu，Mo and Au grade of 2020%，0797% and 2030 g/t and Cu，Mo and Au recovery of 8842%，8039% and 7475% were achieved respectively by the process of one-stage grinding，bulk flotation of one roughing and three scavenging，regrinding of mixed coarse concentrates，one roughing-three cleaning-three scavenging，and middles back to the flow-sheet in turn.

Key words: Porphyry copper-molybdenum ore, Bulk flotation, Regrinding of mixed coarse concentrate