Objective To observe the effects of berberine ( BBR) combined with ethinylestradiol cyproterone acetate in the treatment of obese women with polycystic ovary syndrome ( PCOS) and the influence on vascular endo-thelial function.Methods 50 patients with PCOS were randomly divided into two groups.The observation group was given ethinylestradiol cyproterone acetate 1 piece of qn, BBR 300 mg tid.The control group was given placebo to replace BBR,the other treatment was the same as the observation group.The patients were treated for three menstrual cycles.The two groups were regulated the way of life.Before and after treatment,the body mass index (BMI),waist hip ratio (WHR),follicle-stimulating hormone (FSH),luteinizing hormone (LH),testosterone (T),fasting blood glucose ( FPG ) , fat cholesterol ( TC ) , triglycerides ( TG ) , insulin resistance index ( HOMA -IR ) , select E (E-selection),von willebrand factor (vWF) were tested.Results After treatment,these indicators of fat,sugar, insulin resistance,lipid metabolism disorders of sex hormone,vascular endothelial function in the observation group were more improved than the control group [(23.01 ±1.37),(0.81 ±0.03),(7.85 ±0.98),(4.12 ±0.55), (1.87 ±0.23),(2.56 ±0.67),(7.80 ±2.14),(1.46 ±0.78),(37.13 ±9.02),(142.15 ±43.26)vs (23.57 ± 1.40),(0.86 ±0.04),(87.22 ±11.38),(4.88 ±0.58),(2.25 ±0.24),(4.55 ±0.97),(9.96 ±3.20),(1.67 ±0.80), (24.36 ±7.48),(116.27 ±33.56)],there were statistically significant differences(t=3.85,3.92,4.28,4.32, 4.43,9.14,9.06,6.37,11.35,14.58,all P<0.05).Conclusion BBR combined with ethinylestradiol cyproterone acetate in the treatment of PCOS is not only effectively improved many pathophysiological changes,such as IR,high androgen levels,also protected vascular endothelial function,thereby reducing the risk of cardiovascular disease.