Abstract: A systematic process mineralogy characterization and leaching test study were conducted to address the difficult leaching of Carlin-type gold ore, which is characterized by finely disseminated gold particles （<5 μm）, a high encapsulation rate （67.11 %）, and arsenic （0.40 %） present as arsenopyrite. The results show that under conventional cyanidation with a grinding fineness of −0.074 mm at 90 %, the gold leaching rate was only 32.14 %, classifying the ore as highly refractory. To mitigate insufficient liberation of gold minerals and interference from sulfide minerals, a combined process of "ultrafine grinding, oxidative pretreatment, and cyanide leaching" was proposed. This process increased the ore fineness to −0.010 mm at 80 % through ultrafine grinding and employed pure oxygen for oxidative pretreatment to decompose sulfide minerals. Under conditions of dissolved oxygen concentration of 25 mg/L and oxidation time of 12 h, the oxidation rate of sulfide minerals reached 60.24 %. Subsequent cyanide leaching tests after pretreatment showed that the gold leaching rate increased significantly from 35.32 % in the conventional process to 64.29 %. This approach provides a valuable reference for the development and utilization of finely disseminated and encapsulated refractory gold resources.