Abstract: This study investigates the synergistic preg-robbing behavior of chloride ions and organic carbonaceous matter during the pressure oxidation process of a refractory carbonaceous gold ore from a mining area in Guizhou Province. The effects of chloride ion mass concentration, organic carbon content, reaction temperature, and reaction time on the synergistic preg-robbing effect were examined. Results indicate that preg-robbing is influenced by the presence of organic carbon, chloride ions, as well as the pressure oxidation temperature and time. When gold concentrate and raw ore were blended at a mass ratio of 1∶1, with an organic carbon mass fraction of 4.5 %, a reaction temperature of 210 °C, a reaction time of 55 min, and an activated carbon dosage of 30 g/L, the pressure oxidation followed by carbon-in-leach cyanidation yielded a gold leaching rate exceeding 93.9 %. The preg-robbing effect was effectively mitigated by reducing chloride ion content using silver nitrate as an inhibitor, improving the pressure oxidation performance for the carbonaceous gold ore.