Objective:This study aimed to develop new rice bran products.Methods:The ACE inhibition rate was used as an indicator, and the rice bran protein was optimized by single factor and response surface experiments. The optimal enzyme hydrolysate peptides were separated by ultrafiltration, activity evaluation and amino acid composition analysis were performed.Results:The optimal process conditions were as follows: pH 7.2, mass substrate concentration 8.2 g/100 mL, enzymolysis at 46 ℃ for 3 h, and enzyme addition 0.3 g/100 g rice bran protein. Under the control of these conditions, the ACE inhibition rate of the enzymatic hydrolysate was (73.15±0.64)%, and enzymatic hydrolysate was rich in hydrophobic amino acids (23.09 g/100 g). Activity analysis showed that the ACE inhibitory activity (81.68±1.08)% of ＜3 kDa active peptide component at the same concentration (1.0 mg/mL) was better than those of ＞3 kDa active peptide component (58.65±2.21)% and (72.64± 1.61)%.Conclusion:The rice bran proteolysate obtained under the optimal process conditions has significant ACE inhibitory activity, and the molecular weight of the active peptide component significantly affects its ACE inhibitory activity.