Fibronectin (Fn) is a high molecular dimer of glycoprotein with a series of discrete structural domains. It is composed of three type repeats,type Ⅰ,Ⅱand Ⅲ. A serial repeats form a functional domain. There is only one Fn gene in body, and by alternative splicing it produces many kinds of Fn polypeptides. which have different sequences in three variable regions.Fn is involved in a variety of biological functions. It is very important to elucidate the relationship between the function and structure relationship by deeply analysing the structures of its domains and gene.