Occludin is one of the best characterized protein in tight junction associated proteins,it seals paracellular way to form the basic structure of tight junction.It performs major functions including fence function and paracellular barrier function.Downregulation of occludin protein might induce the disruption of pulmonary epithelial barrier,blood-brain barrier,intestinal epithelium barrier,blood-testis barrier,which has been proved to be associated with the cause and progress of many diseases.Therefore,the regulation mechanism and clinical significance of occludin protein have been the focus at home and abroad.