Objective To investigate clinical characteristics of endocrine hormones and metabolic indicators in the patients of polycystic ovarian syndrome (PCOS) with different body mass index (BMI). Methods A total of 76 patients with PCOS were enrolled. Their age, height, and weight were recorded, and their BMI were calculated. The sex hormone levels, thyroid function, fasting plasma glucose (FPG), fasting serum insulin (FINS), total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were measured, and the homeostasis model assessment of insulin resistance (HOMA-IR) and free androgen index (FAI) were calculated. According to different BMI, the patients were divided into obese, overweight, and normal weight groups, and the differences of endocrine and metabolism indexes among three groups were compared. As HOMA-IR≥2.69 was diagnostic cut-off point of insulin resistance, the proportion of patients with insulin resistance in different BMI groups was calculated respectively. As FAI≥6.1 was the diagnostic cut-off point of hyperandrogenism, the proportion of patients with hyperandrogenism in different BMI groups were also calculated. The chi-square test was used to analyze the difference of the incidence of insulin resistance or hyperandrogenemia in PCOS patients among three groups. Results The levels of sex hormone binding globulin (SHBG) all increased gradually while the levels of FINS and HOMA-IR decreased gradually in the PCOS patients in the obesity, overweight and normal weight groups. The differences had statistical significance among the three groups (P<0.05). Luteinizing hormone (LH), LH/follicle-stimulating hormone (FSH) were significantly lower while thyroid stimulating hormone (TSH) was significantly higher in the obese group than those in both overweight and normal weight groups (P<0.05). FAI, TC, TG, LDL-C in both obese and overweight groups were significantly higher than those in normal weight group (P<0.05). Free thyroxine (FT₄), anti-Müllerian hormone (AMH) and HDL-C in obesity group were significantly lower than those in normal weight group(P<0.05). Spearman correlation analysis showed that BMI was positively correlated with FAI, thyroid-stimulating hormone (TSH), FPG, INS, HOMA-IR, TG, LDL-C (r=0.401, 0.315, 0.362, 0.644, 0.656, 0.582, 0.315 respectively, P<0.05), and negatively correlated with LH, LH/FSH, SHBG, FT₄, AMH, HDL-C (r=-0.364, -0.236, -0.624, -0.304, -0.369, -0.542, P<0.05). The results of the chi-square test indicated that the incidence of insulin resistance and hyperandrogenemia increased gradually in the patients in normal, overweight, and obese groups, and the insulin resistance in the obese and overweight groups was significantly higher than normal weight group (P<0.05), while there was no significant difference between the overweight group and the obese group. In addition, there were statistical difference in hyperandrogenism among three groups (P<0.05). Conclusions The PCOS patients with obesity or overweight have more significant insulin resistance, hyperandrogenemia and abnormal blood lipid metabolism, while the level of pituitary gonadotropin increased more in the PCOS patients with normal weight.