Abstract: The present study aimed to assess the effect of the total flavoniods Ampelopsis grossedentata on(TFA) spontaneously hypertensive rats and normotensive rats,TFA was extracted by ultrasonic method and purified by D-101 macroporous resin. The spontaneously hypertensive rats in experimental group were intragastrically administrated with TFA at 100,200 and 400 mg/kg once a day for consecutive 10 weeks. Rats were given intragastrically with 5 mg/kg enalapril as controls. At end of 10 week,some rats were randomly selected for blood pressure determination and were anesthetized for serum preparation. After keeping normally for 2 weeks,the remaining rats were subjected to blood pressure measurement and serum isolation. The concentration of PRA,ANG Ⅱ,ET,NO,SOD,CAT,GSH,MDA were evaluated. After the healthy SD rats were treated with TFA for 6 months,the blood pressure,the concentration of Na+,K+,Cl-and Na+/K+were measured.TFA significantly reduced the blood pressure,the concentration of PRA,ANG II,ET and MDA in serum and increase the level of NO,SOD,CAT,GSH in primary hypertension rats for 10-week treatment. There was no significant changes in blood pressure of control rats after TFA treatment. TFA significantly reduced the blood pressure in primary hypertension rats. The potential mechanism may be related with the antioxidant system regulation by RAAS. No significant effect was observed on healthy rats. All these suggested that ampelopsis grossedentata showed significant effect on preventing hypertension as natural medicine and natural function food.