Aim To evaluate the characteristics of coronary artery lesion in unstable angina （UA） patients with metabolic syndrome （MS） by intravascular ultrasound（IVUS）. Methods According to being complicated with MS or not, 106 patients with UA were reviewed and divided into MS group（n51） and non-MS group （n55）. The levels of body mass index（BMI）, systolic blood pressure （SBP）, diastolic blood pressure （DBP）, fasting plasma glucose （FPG）, 2h postprandial blood glucose（2hPBG）, total cholesterol （TC）, high density lipoprotein （HDL）, low density lipoprotein（LDL）, triglyceride（TG） were observed. The external elastic membrane（EEM） cross section area, lumens area, plaque area, plaque burden, remodeling index （RI） of coronary arteries and the plaque composition were measured by IVUS in two groups. Results BMI, SBP, DBP, FPG, 2hPBG and TG in MS group were significantly higher than those in non-MS group （P<0.05）. HDL was lower than that in non-MS group （P<0.05）. The plaque area and remolding index in MS group were larger than those in non-MS group（P<0.05）. Compared with non-MS group,there were more necrotic core and less dense calcium in the atheroma plaque of MS group（P<0.05）. Multiple regression analysis showed that FPG, SBP and BMI remained as predisposing risk factors for plaque area levels（P<0.001）. Conclusions From our observasion we concluded that in unstable angina patients with MS, the remolding index, plaque area and the amount of necrotic core material are greater in the culprit vessel. Therefore，the plaque of culprit vessel is more vulnerable.