Objective： To observe the clinical effect of Xiaonang pills combined with routine western medicine for polycystic ovary syndrome(PCOS).Methods：Selected 198 cases of patients with PCOS and randomly divided theminto the control group and the treatment group，99 cases in each group.The control group was treated with progesterone capsules and ethinylestradiol and cyproterone acetate tablets，while the treatment group was additionally treated with Xiaonang pills based on the treatment of the control group.Compared and analyzed curative effect in the two groups，and detected the contents of testosterone(T)，luteinizing hormone(LH)，estradiol2(E 2 )，follicle stimulating hormone(FSH)and LH/FSH ratio in serum.Detected levels of fasting insulin(FINS)， fasting blood glucose(FBG)， body mass index(BMI)and waist/hip ratio(WHR)before and after treatment.Results：The to taleffective rate of the treatment group and the controlgroup was 93.94%and 73.74%respectively，the difference being significant(P ＜ 0.05).After treatment，levels of T，LH and LH/FSH in serumin the two groups were decreased when compared with those before treatment( P ＜0.05).Levels of T，LH and LH/FSH in serumin the treatment group were lower than those in the control group( P ＜0.05).There was no significant difference being found in the comparisons of levels of E 2 and FSH between the two groups before and after treatment(P＞0.05).After treatment， the endometrial thickness in the two groups was increased when compared with that before treatment； the volume of ovary was reduced，the number of antral follicle was reduced.differences being significant( P ＜0.05).The endometrial thickness in the treatment group was larger than that in the control group，and the number of antral follicle was less；the volume of the ovary was smaller，differences being significant(P ＜ 0.05).After treatment，levels of FINS，BMI，FPG and WHR in the treatment group and levels of FINS and BMIin the control group were decreased when compared with those before treatment，differences being significant(P ＜ 0.05).Levels of the four indexes in the treatment group were lower than those in the control group( P ＜0.05).Conclusion：The therapy of Xiaonang pills combined with routine western medicine can obviously improve the levels of sex hormone in serumof patients with PCOS，increase the endometrial thickness，reduce the volume of ovary，reduce the number of antral follicle，and the clinicaleffect is remarkable.