Abstract: The tin ore in a polymetallic sulfide ore in Yunnan has a fine dissemination size，and the proportion of -37 μm particle size is more than 70%，which is a typical refractory tin ore resource. The com‐ bined process of coarse-grained gravity separation and fine-grained flotation is used to recover tin ore on site，but the flotation recovery rate of fine-grained tin ore is low and fluctuates greatly，which seriously af‐ fects the overall tin recovery rate. In order to improve the flotation effect of fine-grained tin ore，the experi‐ mental study of YK series high-efficiency collectors was carried out. The flotation effect of YK-6 was deter‐ mined to be the best under the conditions of YK-6 dosage 700 g/t，P86 dosage 6.8 g/t and 2# oil dosage 31.76 g/t in tin roughing test. The results of closed-circuit test showed that the tin concentrate with tin grade of 6.57% and recovery of 75.42% could be obtained by using YK-6 as collector.The recovery was 5.1 percentage points higher than that of on-site combined collector. In addition，the environmental protec‐ tion performance of YK-6 reagent is excellent，and the indexes of arsenic，ammonia nitrogen，COD，F�and chromaticity in tailings water are better than those of the original reagent，which meets the require‐ ments of green beneficiation. Studies have shown that YK-6 is a fine-grained tin ore flotation collector with strong adaptability，high recovery efficiency and environmental friendliness.

Key words: fine-grained tin ore, floatability, fine-grained