Abstract: P-type semiconductor uhrafine cuprous oxide was prepared and used for the photocatalytic degradation of p-nitrophenol liquid. The main influence factors and levels were ascertained by single factor experiments, and response surface methodology (RSM) was used in optimizing the main influence factors of photocatalytic degradation. Through analyzing the results of response surface methodology experiments, a quadratic polynomial model of photocatalytic degradation for p-nitrophenol by using uhrafine cuprous oxide was obtained. The optimum conditions are the following: the mass concentration of p-nitrophenol solution is 30 mg·L^-1, the volume of H₂O₂ is 0.28 mL, the pH value is 3.6d, and the amount of Cu₂O is 0.11 g. Experiments were carried out under the predicted optimum conditions, the relative error between actual and predicted values is 3.02%, and the actual decolorization efficiency is in good agreement with the predicted decolorization efficiency.