An enzymic hydrolysis of rice protein was studied by using alk. protease and protease B in order to obtain rice protein peptides.And the process optimization was determined by single-enzyme-and double-enzyme-hydrolysis.The results showed that the protein recovery was as high as 43. 9% and the peptides had high sensory score, low bitterness, and small mol. weightCompared with the com. available peptides from soybean protein and fish collagen, the moisture-, protein-, and fat-contents of the peptides from rice protein were similar.Moreover, the proportion of the peptides from rice protein and soybean protein less than 2000 Da were more than 80%, while the peptide from fish collagen was only 58. 01%.The peptide from rice protein was the best in ACE inhibitory activity with the lowest IC_(50) of 4. 94 g/mL.While it was 21. 6% for soybean protein peptide and 14. 1% for fish collagen peptide, resp.Four rice protein peptide sequences were obtained by structural anal., which were in line with the existing structure-activity anal. of ACE inhibitory activity.The ACE inhibitory activity of rice protein peptides produced in different batches showed that the ACE inhibitory rate and IC_(50) were basically stable.