Abstract: In this paper, walnut protein, extracted form defatted walnut meal and then was separated by alkaline extraction- isoelectric precipitation technique, was hydrolyzed by four protease ( alkaline protease, neutral protease, papain and flavor protease) for production of antihypertensive peptides.As an index, ACE inhibitory rate and the degree of hydrolysis were determined to select the proper enzyme with best enzymatic effect.Then single factor experiments were carried out to research the effects of the factors such as substrate concentration ( g / L) , enzyme dosage ( U / g) , hydrolysis time ( h) , hydrolysis temperature ( ℃) and p H. The response surface methodology was used to optimize conditions of the enzymatic hydrolysis. The results showed that the optimum conditions were substrate concentration 30 g / L, enzyme dosage 8000 U / g, temperature 57℃, p H8.6 and time of enzymatic hydrolysis 3h.The ACE inhibition rate could reach 64.32% and the degree of hydrolysis was 21.57%.