Objective To explore the effect of metformin hydrochloride tablets on the clinical efficacy, number of dominant follicles and ovarian volume of polycystic ovary syndrome. Methods 150 patients diagnosed with polycystic ovary syndrome who were diagnosed and treated in our hospital from January 2019 to March 2021 were selected .The patients were divided into observation group and control group by random number table. The control group was treated with letrozole + gonadotropin, and the observation group was treated with letrozole + gonadotropin + hydrochloric acid + Metformin tablets. The clinical efficacy, endometrial thickness, number of high-quality follicles, sex hormone levels, blood lipid levels, and adverse reactions were compared between the two groups. Results ① The effective rate of treatment in the observation group was 90.67%, which was significantly higher than that in the control group, 78.67% (P<0.05). ② After treatment, the endometrial thickness of the observation group was lower than that of the control group, and the number of high-quality follicles was more than that of the control group(P<0.05). ③ After treatment, the levels of Luteinizing Hormone-LH, Follicle Stimulating Hormone-FSH and Testosterone (T) in the observation group were lower than those in the control group (P<0.05). ④ After treatment, the total cholesterol (TC) and triglyceride (TG) in the observation group were lower than those in the control group (P<0.05). ⑤ The incidence of adverse reactions in the observation group was 8.00%, which was significantly lower than 20.00% in the control group (P<0.05). Conclusion Letrozole + gonadotropin + metformin hydrochloride tablets could significantly improve the sex hormone and blood lipid levels in patients with polycystic ovary syndrome, relieve the symptoms of the patients, and improve their uterine condition, which had a good clinical effect.