Abstract: Objectives:The purpose of this paper was to optimize enzymatic conditions of pea protein extrudate by response surface methodology,so as to obtain the optimal antioxidant peptide and set an accurate enzymatic prediction model. Methods:The enzymatic conditions of pea protein by neutral protease were optimized to the scave-nging ratio for O₂^-· by response surface methodology. The separation and molecular weight determination of the hydrolysates were determined by dialysis and high performance liquid phase. Results:The optimal enzymatic co-nditions were as follows:Enzyme amount was 11.80%(E/S),temperature was 37.50 ℃,pH of 6.90,substrate concentration was 8.00%. Under this condition,the O₂^-· scavenging rate was 55.22%±0.2%. It found that the antioxidant activity of the hydrolysate with molecular weight less than 1 ku was the highest and it was up to 60.18% the molecular weight concentrated on 200~800 u was 2~8 peptide. Conclusions:The model confirmed predicts accurately and reliably,and hydrolysates was high antioxidant. The model provided the reference value for related production and process of product development. It was found that the free radical scavenging rate of the peptide could be significantly increased by dialysis.