For a microfine grain gold-bearing sulfide ore,the gold grade is 2.01 g/t and the sulfur grade is 1.29 %.In view of the finely disseminated grain of gold minerals in the ore,which mainly exist in pyrite and gangue minerals in the form of intergranular gold and encased gold,the experimental study on flotation was carried out.The results show that with roughly ground grain -0.074 mm accounting for 85 %,reground grain -0.038 mm accounting for 90 % and the optimum dosage of other reagent,the process that the ore is through once roughing,once cleaning and three times scavenging,the roughing concentrate is reground,and the middling part gathers and returns to flotation closed-circuit flowsheet is adopted and can obtain the gold concentrates with productivity 3.26 %,gold grade 52.40 g/t,gold recovery rate 83.85 %.The flotation index is satisfying.