Abstract: In this experiment, different kinds of proteases were screened to prepare Angiotensin converting enzyme(ACE) inhibitory peptides from Sardine(Sardina melamosticta),and the process of preparing ACE-inhibitory peptides was optimized. The results showed that the combination of papain and Alcalase were the optimal enzymes for preparing ACE-inhibitory peptides from sardine. The optimal conditions of enzymatic hydrolysis were :30%(W/V) of sardine in water was hydrolyzed with 4000 U papain per gram of sardine at70 ℃ and p H7.5 for 2.25 h,in the first enzymatic step and then with 5000 U Alcalase per gram of Sardine at 70 ℃ and p H10.0 for 2.0 h in the second enzymatic step. After optimization,the degree of hydrolysis was up to 28.44% and the ACE-inhibitory rate of the final products was 73.44%.