Objectives: Aim was to evaluate endocrine, metabolic and thyroid parameters which could help to explore the relationship between thyroid function and metabolic changes in Chinese polycystic ovary syndrome (PCOS) patients.Methods: Within a prospective study in PCOS patients compared with healthy women, thyroid parameters were assessed, as well as changes of endocrine, metabolic and clinical characteristics.Results: 144 PCOS patients and 48 normo-ovulatory women matched by age as controls were included. There were significant increases of thyroid-stimulating hormone (TSH), total triiodothyronine (TT3) and total thyroxine (TT4) in the PCOS patients. Body mass index (BMI), waist and hip ratio (WHR), luteinizing hormone (LH), LH/follicle-stimulating hormone (FSH) and total testosterone (T) were significantly higher in PCOS compared with the controls. Total cholesterol (CHO), triglycerides (TG) and apolipoprotein B (ApoB) levels in PCOS were higher, whereas high-density lipoprotein (HDL) and apolipoprotein A (ApoA) were lower compared with the controls. Insulin and homeostatic model assessment of insulin resistance (HOMA-IR) were significantly higher in patients with PCOS.Conclusions: Our study confirms the well-known negative metabolic changes in PCOS patients. The small increases of TSH, TT3 and TT4 level may be related with these metabolic changes in PCOS patients. Further studies may improve the understanding of the relationship between thyroid function and metabolic changes.