To evaluate the effects of Chinese medicine Dingkun Pill () alone or in combination with Diane-35 on patients with polycystic ovary syndrome (PCOS). This is a prospective randomized controlled trial conducted at Peking Union Medical College Hospital Beijing, China, from December 2016 to September 2017. Totally 117 PCOS patients were randomly assigned to the Dingkun Pill group (38 cases), Diane-35 group (40 cases), or combined group (39 cases). Patients in the Dingkun Pill group or Diane-35 group took daily 7 g of oral Dingkun Pill or 1 tablet of oral Diane-35, respectively, for 21 consecutive days followed by 7 drug-free days. And the combined group received a combination of Dingkun Pill and Diane-35. The treatment course was 3 months. Fasting plasma glucose and insulin, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), free fatty acids (FFA) and sex hormones were analyzed, quantitative insulin sensitivity check index (QUICKI) was calculated, and menstruation and acne scores were recorded at baseline and after 3-month treatment. Compared with before treatment, QUICKI decreased significantly in the Dingkun Pill and combined groups after 3-month treatment (P<0.05); TC, LDL-C and FFA decreased significantly in the Dingkun Pill group (P<0.01), LDL-C also decreased obviously in the Diane-35 group (P<0.01), while TC increased significantly in the combined group (P<0.01), TG increased significantly in all groups (P<0.01); total testosterone (TT) and menstruation regularity was improved significantly in the Diane-35 and combined groups (P<0.01); acne scores were improved in all groups (P<0.01). After treatment, TC and FFA in the Dingkun Pill group were significantly lower than the Diane-35 group (P<0.05 or P<0.01); TT was lower and regular menstruation rate was higher in the Diane-35 and combined groups than the Dingkun Pill group (P<0.01), and no differences were observed between Diane-35 group and combined group (P>0.05). Dingkun Pill showed better effects than Diane-35 in improving insulin sensitivity, lowering TC and FFA. Diane-35 was more efficient in regulating menstruation and lowering androgen than Dingkun Pill. Combination of Dingkun Pill and Diane-35 may be a better choice to regulate menstruation, lower androgens while improve glucose metabolism in PCOS patients. (Registered on ClinicalTrials.gov, registration No. NCT03264638).