Abstract: The sulphide ore in tin-rich polymetallic ore severely affects the recovery of tin. At present, there are few reports about biodesulfurization of tin ores at home and abroad. In response to the above problems, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used in the present study to bioleach tin-rich sulphile mineral. The effects of pure and mixed cultures on the biodesulfurization of the tin ore were investigated in shake flask experiments. And dynamics of the two species in the mixed culture were analyzed through the method of quantitative real-time-PCR(qRT-PCR).The results showed that mixed bacteria leaching was better than pure bacteria one and could effectively increase desulfurization rate of the tin ore, so the desulfurizaiton rate reached 97 % on the 18th day (pH 2.0, 30 ℃ and 170 rpm). On the early sixth day of leaching, Acidithiobacillus ferrooxidans accounted for 69.4 % of the total biomass. In the late stage, the content of Thiobacillus ferrooxidans increased gradually and became the dominant strain, which reached 58.3 % in the stable stage (the 24 th day). The above result provides a new idea for the development of biodesulfurization in tin mine.