Abstract: Ferrous iron oxidation rates of microorganisms with different origins were compared. Strains from Chenmengshan, Jiangxi province were selected to do pretreatment experiments. In shaking flasks, the recovery of gold from gold ores by cyanidation with or without bio-pretreatment were compared. Then the influential factors such as pulp density, concentration of Fe³⁺, bio-pretreatment time were studied. The results showed that the gold recovery was improved by addition of 10g/L Fe³⁺. The recovery of gold from refractory gold ores was up to 92.1% with the pretreatment of biooxidation. After four days'pretreatment,the ores could meet the industrial demands.