Abstract: Gold has important strategic significance and economic value. At present， cyanidation is mainly used to extract gold in the industry. However， cyanidation has a long production cycle and the cyanide used is highly toxic. If it is not well managed， there will be potential environmental pollution risks. Taking the gold-bearing acid residue of a gold smelter as the research object， the leaching of gold in a thiourea system was studied. The results show that the leaching rate of gold from gold-bearing acid residue is only 83.17 % under the condition of conventional intensified stirring thiourea leaching. Under the condition of ultra-fine grinding to enhance thiourea leaching， the gold leaching rate of gold-bearing acid residue reaches 89 %； it is recommended that the best experimental scheme is enhanced stirring leaching + one stage ultra-fine grinding leaching + two stage ultra-fine grinding leaching for three times + enhanced stirring leaching. The leaching rate of gold from gold-bearing acid residue can reach 95.04 %， which can realize the clean and deep extraction of gold from gold-bearing acid residue and provide theoretical and technical support for the industrial application of the non-cyanide gold extraction process.