The purpose of this paper was to optimize the enzymolysis conditions of pea protein with enzyme combined extrusion by response surface methodology, so as to obtain the optimal antioxidant peptide with high free radicals scavenging capacity and an accurate enzymolysis prediction model. The enzymolysis conditions of neutral protease were optimized with the scavenging ratio of O2-.as evaluation index and with water content of 30% pea protein as raw by response surface methodology. The optimal enzymolysis conditions were as follows: enzyme amount 12.23% (E/S), temperature 40.23℃, pH 6.99, and substrate concentration 6.92% (g/mL). Under these conditions, the O2-.scavenging rate was 75.93%. The separation and determination of molecular weight of enzymolysis products were studied by the combination of dialysis and HPLC. The enzymolysis liquids with molar weights <1 ku, 1~3.5 ku, 3.5~7 ku, and<7 ku were separated. The results showed that the antioxidant activity of enzymolysis liquid less than 1 ku was the strongest, reaching 78.31%. The molecular weight was concentrated in about 200 ~ 800 u as 2 ~ 8 peptide. It is confirmed that the prediction model is accurate and reliable, and hydrolysates has high antioxidant activity, which can provides the reference value for the development of related production and process products. Dialysis can significantly improve the free radical scavenging rate.