Abstract: A gold ore in Gansu Province is a low-grade oxidized ore.Gold mineral is natural gold,which mainly exists as fine grain gold,and occurs as wrapped gold,accounting for 37.04%.Based on analysis of the gold ore characters,the three schemes of conventional floatation,gravity separation and all-sliming cyanidation were carried out.By comparing the three processes,all-sliming cyanidation was confirmed to recover gold as the best process.The optimal conditions were achieved by optimizing the influence factors of all-sliming cyanidation index,they are grinding size of 85%,-200 mesh,PH is 10-11,protective alkali of CaCO₃ 2000g/t,leaching time 4hours,pulp concentration 40%,The bottom carbon density 15g/l,adsorption time 8hours.Comprehensive conditions parallel test of cyanide carbon-in-leach was carried out at the optimal conditions,and 90% of gold leaching rate,99.45% of gold adsorption rate and 92.63% of total gold recovery rate can be obtained.