Abstract: To solve the problems of the low lead-tin concentrate index in Dachang Plant in Guangxi Province resulted from high content of pyrrhotite in lean indium-tin poly-metallic sulfide ore，decrease of lead and stibium grade，and unsatisfied performance in lead-stibium flotation by collector leading to non-ideal lead-stibium concentrate index，the tests of pyrrhotite separation by low intensity magnetic separation，and lead-stibium mixed floatation were conducted to find the optimum conditions.Results indicated that，at the grinding fineness of 46.88% passing 0.074 mm，through one stage low intensity magnetic separation for pyrrhotite(at field intensity of 120 kA/m)，and with butylamine dithiophosphate，amino dithiophophate and DY as combined collector via one roughing-two cleaning-two scavenging lead-stibium bulk flotation，lead-stibium mixed concentrate with Pb+Sb grade of 55.08%，lead recovery of 93.22%，stibium recovery of 90.94%，and 4.61% Zn was obtained.Compared with on-site process，Pb+Sb grade increased by 2.91 percentage points，lead recovery increased by 7.06 percentage points，stibium recovery increased by 5.13 percentage points，zinc content decreased by 0.58 percentage points.The result pronouncedly indicates that the combined agent of butylamine dithiophosphate，amino dithiophophate，and DY is a new high efficient collector of lead-antiomony mixed flotation.

Key words: Lean indium-tin polymetallic sulfide ore, Pyrrhotite, Jmaesonite, Lead-antimony mixed floatation, Combined collector