Abstract: Enzymatic hydrolysis preparation process of angiotensin-I converting enzyme (ACE) inhibitory peptides from Antarctic krill (Euphausia superba) was optimized and its stability was evaluated. Using the degreased Antarctic krill meal as the substrate and the ACE inhibition rate of enzymatic hydrolysates as the evaluation index, alkaline protease was selected as the optimal protease for preparing ACE inhibitory peptides from Antarctic krill among six types of proteases. The optimum enzymatic hydrolysis conditions were determined through single factor and response surface experiments, which were finally confirmed as follows: Enzymatic hydrolysis time of 3.4 h, material liquid ratio of 1:7 (g/mL) and enzyme dosage of 1.6%. Under these conditions, the ACE inhibition rate of enzymatic hydrolysates was 74.37%±0.87%. The obtained ACE inhibitory peptides exhibited good thermal stability at temperatures ranging from 20 ℃ to 100 ℃ and were relatively stable under neutral and weak alkaline conditions. The ACE inhibitory activity of the peptides decreased significantly under pH<7.0 and pH>8.0 conditions (P<0.05). The peptides could maintain 86.96% of the original ACE inhibitory activity after simulated gastrointestinal digestion in vitro. The present research provides scientific support for the development of Antarctic krill protein-derived healthy foods and food-derived peptides-based antihypertensive drugs.