Abstract：Objective：To observe the clinical effect of Ziyin Zhuyang prescription combined with metformin for polycystic ovary syndrome(PCOS). Methods：A total of 90 cases of PCOS patients were selected and divided into the observation group and the control group according to the admission number，45 cases in each group. The control group was given metformin hydrochloride tablets， and the observation group was additionally treated with Ziyin Zhuyang prescription based on the treatment of the control group. Both groups were treated for three courses， one menstrual cycle being a course. The hormone levels，endometrial thickness，as well as pulsatility index(PI) and resistance index(RI) of uterine spiral artery were compared between the two groups before and after treatment. The clinical pregnancy rate and biochemical pregnancy rate in the two groups were compared. Results： After treatment， the levels of follicle stimulating hormone(FSH)， luteinizing hormone(LH)， testosterone(T) and anti mullerian hormone(AMH) in the two groups were decreased when compared with those before treatment(P＜0.05)， and the four levels above in the observation group were lower than those in the control group(P＜0.05). After treatment，the endometrial thickness of two groups were increased when compared with those before treatment(P＜0.05)，and PI and RI of uterine spiral artery were decreased when compared with those before treatment(P＜ 0.05)；the endometrial thickness in observation group was larger than that in the control group(P＜0.05)，and PI and RI of uterine spiral artery were lower than those in the control group(P＜0.05). The biochemical pregnancy rate was 26.67% in the observation group，lower than that of 42.22% in the control group(P＜0.05). The clinical pregnancy rate was 55.56% in the observation group ， higher than that of 22.22% in the control group(P＜0.05). Conclusion： The therapy of Ziyin Zhuyang prescription combined with metformin in the treatment of PCOS can effectively regulate hormone levels， enhance the endometrial thickness，improve the PI and RI of uterine spiral artery，and enhance the clinical pregnancy rate.