Objective:To explore the mechanism of pioglitazone(PGZ)on brown adipose tissue(BAT)function in insulin resistance and type 2 diabetes mellitus, by using high fat diet-induced obesity(HFD)mouse. Methods:The C57BL/6J mice were randomly divided into the normal diet group and high-fat diet(HFD)group. After 20 weeks,the HFD group mice were randomly divided into obese control group and PGZ treatment group.They were orally administered placebo and PGZ[10 mg/(kg·d)]respectively for one month. The levels of body weight,serum insulin and oral glucose tolerance were measured by Biochemistry technology; The effect of pioglitazone on brown adipose tissue(BAT)was assessed by real-time quantitative PCR and Western-blot. Results:The bodyweight, serum insulin levels increased(P < 0.05)and oral glucose tolerance decreased in HFD group. Comparing to obese controls,serum insulin,glucose levels significantly decreased(P < 0.05),and oral glucose tolerance increased in PGZ treatment group; The expressions of proteins and mRNA relative to BAT function increased in PGZ treatment group. Conclusion:PGZ can enhance the function of BAT by regulating BAT relative gene and protein expressions, and may be the important reason of improving insulin resistance and metabolism in HFD mouse.