Objective To investigate the effects of serum 25-hydroxyvitamin D on insulin resistance and IVF pregnancy outcomes in the patients with PCOS. Methods The patients with PCOS were divided into vitamin D deficiency group and sufficient group according to the concentration of serum vitamin D. To compare and analyze the relationship between 25(OH) D and indicators of insulin resistance and secretion function in patients, and effects on pregnancy outcomes. Results VDD group with significantly higher proportion of high risk of 1h postprandial blood sugar, hyperinsulinemia and insulin resistance, but with significantly lower ISIcomp (P<0.05). G60、 time-glycemic AUC has predictive value on VDD in PCOS. Vitamin D sufficient is in favor of improving the quality of embryos (r=0.3, P=0.014), but does not affect IVF pregnancy outcomes. Conclusion VDD of the patients with PCOS incline to be combined with insulin regulatory dysfunction, but it has no harm to IVF pregnancy outcomes.