Objective: The aim of this study was to observe clinical curative effects of combination application of dimethylbiguanide and pioglitazone and single application of pioglitazone in patients with polycystic ovarian syndrome (PCOS) complicated with insulin resistance (IR). Materials and Methods: Forty cases of patients with PCOS complicated with IR were investigated, and 20 cases of infertile women without PCOS were taken as the control group. PCOS group was divided into group A and group B according to body mass index (BMI) to detect glucose and lipids metabolism indicators, C reactive protein (CRP), etc. There were 20 cases in group A (Pioglitazone) and 20 cases in group B (dimethylbiguanide and pioglitazone). After treatment for 12 weeks, changes of the above various indicators were compared. Results: After treatment, insulin resistance index and serum testosterone (T) of two groups patients with PCOS significantly reduced (p < 0.05). Compared to before treatment, BMI of group B significantly reduced (p < 0.05). For INS at two hours after treatment, group B reduced more significantly (p < 0.05). Conclusion: The combination of dimethylbiguanide and pioglitazone was more effective for the treatment of PCOS complicated with IR than simple pioglitazone; chronic inflammation occurrence was possibly one of reasons for insulin sensitivity reduction of patients with PCOS.