Based on the theoretical analysis of aqua regia reduction by controlling potential,the terminal potential interval of IC-Au99.99 production by selective reduction is determined.The optimum conditions of producing IC-Au99.99 were obtained through the experiment.Under the optimum conditions that the dilution coefficient of gold leaching solution is 2.0,the sedimentation time is 18 h,the reduction rate is 50 minutes per kettle,the reduction temperature is 50 ℃ and the reduction terminal potential is 740 mV.The purity of gold reaches more than 99.997 %,the quality of gold powder is stable and reaches the standard of IC-Au99.99,the primary reduction rate of gold in a single time is more than 96 %,and the recovery rate is greater than 99.99 %.