This paper presents the development of a three-dimensional finite element model of central maxillary incisor. Stress distribution of the periodontal membrane was obtained by calculation under physiological load exerted to the natural tooth and tooth restored with post respectively. And it was compared with the stress distribution of the implate (contact with bone and without periodontal membrane). The result indicated that, under physiological load, when the natural tooth was compared with tooth restored with post, there were no apparent diferences in stress distribution of periodontal membrane and in stress values on inner surface and outer surface of periodontal membrane. It suggests that periodontal membrane has apparent cushioning action against stress.