Abstract: Objective:Using 12-week-old male SHR and Wistar rats as the trial animals, they were gavaged casein bi-enzymatically (pepsin and trypsin) hydrolysates (A) , the ultrafiltration (B) , debittering (C) products of the hydrolysates, and ultrafiltration of debittering products (D) respectively, in order to study their antihypertensive effect.Methods:In the study, the gavage administration doses of A and C was 0.083, 0.25 and 0.75g/kg mb, B and D was 0.01, 0.03 and 0.09g/kg mb.The SHR were tested for their systolic blood pressure (SBP) during 8 hours post-administration.Results:normal Wistar rats administered high dose of the four products did not present any obvious change after administration, each of the three doses about the four products had a notable inhibitory effect on the increase of SBP in SHR, the four hydrolysates (A, C, B and D) achieving the highest reduction 22.630, 19.375, 33.375, 29.000mm Hg in the fourth hour at the administered dose 0.25, 0.75, 0.03 and 0.03g/kg mb respectively.The blood pressure of SHR rats dropped with 36.875, 31.875mm Hg at four hour after administered the fermented milk produced by the two ultrafiltration products, furthermore, continuous administration of the two yoghurt could keep SBP at a lower level for a long time period.Conclusion:There were certain effect on control and treatment about high blood pressure using functional yoghurt containing rich ACE inhibitory peptides, and providing a certain basis for antihypertensive food.