Thiosulfate leaching of gold has many advantages,such as a fast leaching rate,low toxicity,is applicable to dealing with refractory gold ores containing copper,arsenic,and carbon,and is considered the most promising non-cyanide leaching technology to replace cyanide gold extraction.In this paper,the slag obtained from a two-stage roasting pretreatment of the refractory gold concentrates with high arsenic content in a domestic gold enterprise contains 104 g/t Au,0.74 % As,and 0.87 % S.The completely randomized design decided the adoption of the copper-ammonia-thiosulfate method to extract gold from the slag.The optimal leaching conditions for thiosulfate leaching are as follows:0.10 mol/L Cu^2＋,2.0 mol/L NH₃·H₂O,0.10 mol/L Na₂S₂O₃,solution pH of 11,temperature of 50 ℃ and leaching time of 7 h.Under these conditions,the maximum gold leaching rate is 75.1 %,indicating that the application of the thiosulfate leaching process to this slag still needs to be further optimized and strengthened.