Integrin is one kind of cell adhesion molecules which is distributed widely at cell surface. The structure and function of integrin was introduced.Integrin is a noncovalent associated heterodimer composed of α and β membrane-spanning subunits.It is involved in the adhesion between cell and cell,cell and extracelluar matrix.The signal transduction outside in was mediated by tyrosine kinase and protein kinase C. The alteration of integrin expression quality and quantity could be occured during carcinogenesis.