To investigate the effect of dydrogesterone combined with pioglitazone for treating patients with polycystic ovary syndrome (PCOS), and to study its influence on the insulin resistance, the ovarian function and the levels of serum anti Mullerian hormone (AMH) and follicle-stimulating hormone (FSH) of the patients with polycystic ovary syndrome. Methods: A total of 147 patients with PCOS were selected and were divided into 74 patients in observation group and 73 patients in control group randomly according to the random number table method from September 2020 to May 2023. The patients in the two groups were treated with dydrogesterone starting from the fifth day of the menstrual cycle, and the patients in the observation group were treated with pioglitazone additionally. The efficacy, the changes of the fasting blood glucose (FPG) and fasting insulin (FINS) levels, the value of homeostasis model assessment of insulin resistance (HOMA-IR), the number of follicles, the ovarian volume, and the levels of AMH, FSH, testosterone (T) and luteinizing hormone (LH) levels before and after treatment, and the adverse reactions rate of the patients were compared between the two groups. Results: The total effective rate (96.0%) of the patients in the observation group was significantly higher than that (84.9%) of the patients in the control group. The levels of the FPG and FINS, the HOMA-IR value, the number of follicles, the ovarian volume, and the levels of AMH, FSH, T and LH of  the patients in the two groups after treatment had decreased significantly. The levels of the FPG and FINS of the patients in the observation after treatment were significantly lower than those of the patients in the control group. The HOMA-IR value, the number of follicles, the ovarian volume, and the levels of AMH, FSH, T and LH of the patients in the observation after treatment were 2.14±0.49, 7.11±0.76, 23.18±3.04ml, 20.96±4.52 pmol/L, 5.19±0.51 mIU/ml, 40.76±5.38 nmol/L and 3.27±0.83 mIU/ml, respectively, and which were significantly lower than those (3.19±0.97, 11.19±1.24, 31.51±4.13ml, 28.75±5.64 pmol/L, 5.56±0.63 mIU/ml, 51.65±6.24 nmol/L and 5.54±1.01 mIU/ml, respectively) of the patients in the control group (all P＜0.05). There was no significant difference in the incidence of the adverse reactions (9.5% vs.6.5%) of the patients between the two groups (P＞0.05). Conclusion: Dydrogesterone combined with pioglitazone for treating the patients with PCOS has higher therapeutic effect, and which can correct the insulin resistance, improve the ovarian function, reduce the serum AMH and sex hormone levels of the patients, and with the good safety.