Abstract: Antihypertensive peptides were made from pig scapula protein through ultrasonic assisted flavourzyme enzymatic method and drew a parallel between them with those without ultrasonic pretreatment. The single-factor method was used to analyze the effect of ultrasonic power, ultrasonic time, ultrasonic temperature, on-time and off-time of ultrasonic, enzymolysis time after ultrasonic on Angiotensin-converting enzyme (ACE) inhibitory activity of pig scapula protein hydrolysate. Operating parameters such as ultrasonic power, ultrasonic time and ultrasonic temperature were optimized using response surface analysis based on ACE inhibitory rate.The results indicated that the optimal ultrasonic conditions of pig scapula peptide were ultrasonic power of717 W, ultrasonic time of 25 min, ultrasonic temperature of 40℃, on-time and off-time of 1∶1.5 (s/s) , enzymolysis time after ultrasonic of 3h.The theoretical value of ACE inhibitory activity was 75.29%, which was close to the actual value of 75.58%.It was 10.27% higher than that of the peptides without ultrasonic pretreatment. Half-inhibitory concentration (IC50) decreased by 32.8%, enzymolysis time shorten by 1.5h.