Abstract: Abstract: Angiotensin-converting enzyme (ACE) inhibitory peptides made from hydrolysis of pumpkin seed meal with neutral protease is one of the important ways to utilization pumpkin seed meal. In order to find the optimum craft of ACE inhibitory peptides made from pumpkin seed meal by protease, taking ACE inhibitory rate as the response value, protease content，the effects of substrate content，and hydrolysis time on ACE inhibitory activity of the hydrolysates were analyzed with response surface methodology for optimization of the preparation technology．The results showed that the three factors affecting activity of ACE inhibitory peptides significantly (P<0.001). The optimized parameters for preparation of angiotensin-converting enzyme inhibitory peptides were temperature at 45℃ and pH value of 7.0, the protease content 4.8%, substrate content of 4.0 g/100mL, and hydrolysis time of 320 min. With the optimal parameters, the ACE inhibiting percentage theoretically could be up to 80%. The validation test showed that the actual ACE inhibiting percentage was 80.56%±0.23%, which was closer to 80%. It suggested that the established prediction model is reliable. The results here proposed the viable and reliable optimization parameters for preparation of ACE inhibitory peptides.