Objective To investigate the effect of reducing blood pressure of casein hydrolyzed peptide powder（CH）compound and its results of toxicity after 30-day feeding.Methods 16 SD rats and 56 spontaneously hypertensive rats（SHR）were chosen to do effect experiment.16 SD rats were divided into a control group fed with distilled water and a treatment group fed with compound sample solution

8in each group;according to their blood pressure and body mass

56 SHR rats were randomly divided into model group

bezoar buck capsule group

CH compound groups of low

medium and high dose（low

medium and high dose compound groups）

CH group and traditional Chinese medicine（TCM）group

8in each group

and all groups were given gastric perfusion once a day for 30 days.Another 20 SD rats were randomly divided into a control group giving distilled water and a compound group giving compound sample solution

10 in each group

and both were administered once a day for 30 days.Rats′systolic blood pressure

diastolic blood pressure and heart rate were recorded

and serum nitric oxide（NO）

angiotensinⅡ（AngⅡ）

endothelin-1（ET-1）and other indicators were tested.Results After 30-day administration

the systolic blood pressure and diastolic blood pressure of bezoar buck capsule group

low-dose compound group

medium-dose compound group

high-dose compound group

CH group and TCM group were significantly lower than the model group and the differences were statistically significant（P<0.05）;the systolic blood pressure and diastolic blood pressure of medium-dose compound group were significantly lower than CH group and TCM group and the differences were statistically significant（P<0.05）.There were no significant differences in heart rate between before and after 30-day administration.After 30-day administration

there were significant differences in serum AngⅡ

NO and ET-1levels between the model group and bezoar buck capsule group

low-dose compound group

medium-dose compound group

high-dose compound group

CH group and TCM group（P<0.05）;serum AngⅡlevel in rats of medium-dose compound group was significantly lower than TCM group

NO level was significantly higher than CH group

ET-1level was significantly lower than CH group and the differences were statistically significant（P<0.05）.30-day feeding test showed there were no significant differences in general signs between the compound group and the control group.The differences in body mass of 7-day

14-day

21-day and 30-day feeding were not statistically significant.There was no obvious abnormality in the size and shape of rats′main organs in the compound group and the control group and their differences in organ coefficient of liver

kidney

spleen and testis were not statistically significant.Total protein level in rats of the compound group was higher than the control group and the difference was statistically significant（P<0.05）;there were no significant differences in the other blood biochemical parameters between the two groups.Conclusion Casein hydrolyzed peptide powder compound can reduce blood pressure and its effect is better than each single component of the compound;there was no significant toxicity in 30-day feeding.