OBJECTIVE： To observe the protective effect of total flavonoids from Ampelopsis megalophylla on cardiac tissue of spontaneously hypertensive rats （SHR）， and to investigate its mechanism. METHODS： 50 SHRs were randomly divided into model group， Compound apocynum tablets group （positive drug， 50 mg/kg） and total flavonoids from A. megalophylla low-dose， medium-dose and high-dose groups （90， 180， 360 mg/kg）， with 10 rats in each group. The rats were given relevant medicine intragastrically， and model group was given constant volume of distilled water intragastrically， twice a day， for consecutive 7 weeks. Blood pressure of rats were determined and cardiac index of rats were calculated； the morphology and structure of cardiac tissue were observed by HE staining. mRNA expression of ACE， AngⅡ and CYP11B2 in cardiac tissues were determined by RT-PCR. RESULTS： Total flavonoids from A. megalophylla can significantly decrease the blood pressure of SHR （P＜0.01）， improve the flammatory lesions of  hearte  issue  such as  irregular cell morphology， cell shrinkage， proliferation of fibrous tissue and so on， and it also can significantly decrease the mRNA expression levels of ACE， AngⅡ， CYP11B2 in cardiac tissue of rats （P＜0.05 or P＜0.01）. CONCLUSIONS： Total flavonoids from A. megalophylla can protect cardiac tissue of SHR， the mechanism of which may be associated with down-regulating mRNA expression of ACE， AngⅡ and CYP11B2 in cardiac tissue.