Vitamin D is classic metabolism regulator of the calcium and phosphorus. Type 2 diabetes is main charac-terized by insulin resistance and beta cell function impairment, which causes insulin secretion defects and synthesis ab-normality. In recent years, studies found close relationship between vitamin D and type 2 diabetes; Many basic re-searches and animal experiments show that vitamin D can improve insulin resistance, protect islet beta cells and have immune regulation effects in the development of type 2 diabetes Diseases. Vitamin D can regulate and control islet function by inhibiting islet beta cell apoptosis, promoting the secretion of pancreatic beta cells and weakening the se-cretion of islet alpha cell. This paper reviewed the research progress in recent years on the correlation between vitamin D and islets function.