Aim To investigate the high density lipoprotein （HDL） subclasses distribution characteristics before and after the intervention of Pioglitazone in obesity people with impaired glucose tolerance. Methods The difference of plasma HDL subclass distribution was compared in 40 cases of healthy people and 40 cases of obesity people with glucose tolerance, to investigate the plasma HDL and class distribution characteristics in obesity people with impaired glucose tolerance. Using the randomized matching design method （the sex as the condition）,forty men were randomized,to placebo or pioglitazone （30 mg/day） for 12 weeks. The subclasses of serum HDL were determined by two dimensional gel electrophoresis in conjunction with immunodetection method and paraoxonase-1 activity by spectrophotometric assays. The correlation between the distribution of plasma HDL subclasses and the activity of PON-1 were analyzed. Results Compared to the health group, the HDL2a and HDL2b decreased while the preβ1-HDL, preβ2-HDLand HDL3a increased significantly in obesity man with glucose tolerance. Compared to the control group, the preβ1-HDL decreased while the HDL2a and HDL2b increased and activity of PON-1 increased significantly in Pioglitazone group after 12 weeks. PON-1 is positively correlated with HDL2b,and negatively correlated with preβ1-HDL. Conclusion Obese patients with abnormal glucose tolerance handicaped the mature process of serum HDL, tended to have weaker resistance from atherosclerosis. Pioglitazone improved the distribution of HDL subclass and increased the activity of PON-1 in overweight and obese men with impaired glucose tolerance,which may help reduce the incidence of premature cardiovascular disease. The activity of PON-1 is positively correlated with mature distribution of HDL subclasses.