The surface of oral mucous is highly specialized stratified squamous epithelium that plays an important role in protecting the tissue beneath it from physical, chemical or biological damages. However, the change of the epithelium structure as well as the related deficiency in functions due to some genetic or immunological factors have already become the obstacle of patients' life quality and clinical treatment. Recently, with the development of molecular biology and genetic technology, more and more researches have been done on the epithelia microstructure, and a better understanding has been made not only of the epithelia constructive protein which takes an important part in maintaining the integration and functions of the epithelium tissue, but also of the pathology of some human hereditary and acquired diseases related to the abnormality of epithelium constructive protein. In this way, it provides a new direction for the diagnosis and therapy of this kind of diseases.