Abstract: Water quenching slags were leached by oxygen pressure at the acidic conditions. The effects of ratio of oxygen pressure temperature, sulfuric acid concentration, liquid-solid ratio on the selective leaching were investigated using response surface methodology for optimal and analysis. Optimal process parameters on Mn leaching from water quenching slags and two order polynomial equation of model were obtained. At the optimal conditions as follows, the oxygen pressure temperature of 171.4 ℃, sulfuric acid concentration of 48.62 g/L, liquid-solid ratio of 6.42. The results show that the theoretical leaching ratio of model predicts can reach 95.59%, while the experimental average values are 95.61%.