Abstract: Antioxidant peptide was prepared by alkaline protease enzymolysising Chinese chestnut protein and its antioxidant activity determined.The craft was obtained with the degree of hydrolysis and the DPPH· scavenging ratio as indicators by single factor tests primarily,then according to Box- Behnken central composition design principle,the method of response surface analysis with 4 factors and 3 levels combined with Design Expert 8.0-statistical data analysis software was adopted to establish the regression equation prediction model of enzyme dose,enzymolysis temperature,enzymolysis p H and enzymolysis time and the DPPH· scavenging ratio as the response value.The optimum preparation conditions were established as follows: enzymedose 2.5%,enzymolysis temperature 50 ℃,enzymolysis p H9.5 and enzymolysis time 3.7 h.Under these conditions,the DPPH· scavenging ratio reached 92.86%,consistent with the theoretical value.