Aim To observe endothelium-dependent relaxing function of the patients with hyperlipidemia and coronary heart disease (CHD) and explore their clinical significance. Methods 20 cases with hyperlipidemia, thirty cases with CHD confirmed by coronary angiography were classified as two groups, CHD group Ⅰ with 17 cases, and CHD group Ⅱ with 13 cases. 20 healthy individuals are as control group. Brachial endothelium-dependent relaxing function was detected with high-resolusion ultrasound. Results Basic diameters of brachial arteries in four groups had no differences. Flow- mediated dilatations of brachial arteries in the group of hyperlipidemia, CHD group Ⅰ, CHD group Ⅱ were significantly reduced compared with control group (P<0.05,P<0.01,P<0.01). CHD group Ⅰ, CHD group Ⅱ were significantly droped compared with the hyperlipidemia (P<0.05,P<0.01). There was also significant difference between CHD Ⅰ and Ⅱ groups (P<0.01). After being sucked nitroglycerin the diameters of brachial arteries in four groups were all variously dilated. But CHD groups were signifficontly reduced compared with control group and group of hyperlipidemia(P<0.01,P<0.01). There was no significant change between CHD Ⅰ and CHD Ⅱ. There was no significant change between control group and group of hyperlipidemia. Conclusions Endothelium-dependent relaxing function was gradually reduced with the severity of atherosclerosis. It was confirmed that there is a relation between endothelium- dependent relaxing function by high -resolusion ultrasound and severity of atherosclerosis in coronary arteries and peripheral arteries.