Abstract Objective： To observe the clinical effects of Xionggui Erchen Decoction combined with Metformin in treating polycystic ovary syndrome (PCOS) and its effects on the menstrual cycle of patients. Methods：A total of 86 patients with PCOS were selected and randomly divided into the observation group and the control group， with 43 cases in each group. The control group was treated with Metformin， and the observation group was additionally treated with Xionggui Erchen Decoction based on the treatment of the control group. The clinical effects， traditional Chinese medicine (TCM) syndrome scores， menstrual cycle changes， and changes in the levels of glycolipid metabolism indicators [total cholesterol (TC)， triglycerides (TG)， fasting blood glucose (FBG)， and 2-hour postprandial blood glucose (P2hBG)] were compared between the two groups. Results：The total effective rate in the observation group was 95.35%， while that in the control group was 76.74%，with the difference being significant (P＜0.05). After treatment， the TCM syndrome scores in the two groups were decreased when compared with those before treatment (P＜0.05)， and the scores in the observation group were lower than those in the control group (P＜0.05)； the menstrual cycles in the two groups were shortened when compared with those before treatment (P＜ 0.05)，and the menstrual cycle in the observation group was shorter than that in the control group (P＜0.05). The levels of TC， TG， FBG， and P2hBG in the two groups were decreased when compared with those before treatment (P＜0.05)，and the levels of the above indicators in the observation group were lower than those in the control group (P＜0.05). Conclusion： The combination of Xionggui Erchen Decoction and Metformin can effectively improve the TCM syndromes and menstrual cycle of PCOS patients，reduce the levels of blood glucose and lipids，and enhance clinical efficacy.