Abstract: In this paper, based on the single-factor experiment, the response surface method was used to optimize the ultrasonic-assisted enzyme extraction process of Cyperus esculentus ACE inhibitory peptide, and the best auxiliary enzyme was selected through the inhibition experiment of angiotensin converting enzyme. The results showed that the optimal process conditions for the ultrasonic-assisted enzymatic extraction of Cyperus esculentus ACE inhibitory peptides were: Substrate concentration 3%, ultrasonic treatment time 20 min, enzymolysis temperature 45 ℃, enzyme addition 5000 U/g, ultrasonic power 180 W, enzymolysis time 3 h, the best auxiliary enzyme-alkaline protease, under this condition, the ACE inhibition rate was 74.16%. This study would provide a theoretical basis for the extraction of Cyperus esculentus ACE inhibitory peptides, which laid a foundation for further research on Cyperus esculentus ACE inhibitory peptide.