Aim To explore the influence of Guizhi Tang to vascular endothelial active substances in rats with experimental hyperlipemia and myocardial ischemia.Methods The early changes of hyperlipid and atherosclerosis were caused by utilizing multiple factors including feeding hyperlipid,propylthiouracil and high doses of VD3.Based on the above,the myocardial ischemia model was established by injecting high doses of pituitrin.The total cholesterol(TC),triglyceride(TG),high density lipoprotein cholesterol(HDLC) and low density lipoprotein cholesterol(LDLC) were measured in the 6th,12nd and 18th week respectively,and also the content of endothelin(ET),6-ketoprostaglandin F1 alpha(6-keto-PGF1α),thromboxane B2(TXB2) and angiotensin Ⅱ(AngⅡ) were determined.Results Guizhi Tang significantly improves the indexes of blood lipid metabolism,decreases TC,TG and LDLC,and increases HDLC.Guizhi Tang decreases ET,AngⅡ and TXB2 of blood serum,and increases 6-keto-PGF1α.Conclusion Guizhi Tang can regulate the function of vasoactive substance,protect endothelial cell and inhibit the formation of atherosclerosis.