Abstract: Gold in a high-As and high-S gold concentrate was mainly electrum.Gold is mainly hosted in pyrite and arsenopyrite.Au-carrier minerals are fine disseminated in sulfide minerals，hitherto regarded as difficult to be extracted with conventional CIP（Carbon in Pulp) process.Biooxidation pretreatment and cyanide-free gold leaching were investigated to extract gold by a high-effective and low toxicity method.The mixture of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans was used as oxidation pretreatment microorganism.For gold concentrate（46.87 g/t Au，8.56% As，15.08% S) with particle size of less than 45 μm，at pH=2，pulp density of 120 g/L，initial ［Fe²⁺］=1.5 g/L，and inoculum of 20%，bio-oxidation pretreatment for 12 d，and novel cyanide-free reagent dosage of 4 kg/t leaching for 4 h，the extraction rate of gold can reach 81.67%，higher than CIP of 60 percentage points.The gold leaching index is good.

Key words: Arsenic bearing refractory gold ore, Biooxidation, Cyanide-free gold leaching