Abstract: Peanut dregs were as raw materials and then enzymatic hydrolysis of peanut protein isolates ( PPI) was optimized by response surface methodology ( RSM) .Alcalase was screened as a suitable protease for hydrolysis of PPI.The effect of temperature, enzyme amount and pH on the PPI hydrolysis were investigated and the RSM was further applied on the basis of the single factor experiment.The mathematic model was built between the degree of hydrolysis ( DH) and three factors, and then the interactions among every two factors were analyzed. The optimal conditions for obtaining the highest DH were determined to be 53.11℃ of hydrolysis temperature, 135.94 μL /g of enzyme concentration and 8.05 of pH. The hydrolysis degree of PPI was 24.15% under the optimized hydrolysis conditions.This actual result was basically consistent with the predictive value ( 24.57% ) of the fitting equation.