Tooth loss due to severe caries or trauma is often observed in clinical dentistry After endodontic teatment， dentists can adopt a post/core system to recover the root canal and provide retention for crowns. Thedesigns of the post were one of the major biomechanical concerns in clinical application. Theobjective of this study was to investigate the effects of various designs (including lengths， diameters， and materials) of posts used in endodontically treated premolar on endodontically treated premolar using fIniteelement (FE) analysis A healthy premolar with no caries or other complications was selected for the construction of the FE models. All exterior nodes at the mesial and distal alveolar bone surfaces were fIxedin all directions as the boundary condition. Anoblique force of lOON was applied (45 degrees with buccal inclination) on the buccal occlusal surface. Threediameters (l.8，1.5， and 1.2 mm)， 3 lengths (2， 8， and 6 mm)， and 3 materials (zirconium， titanium and gold alloy) were investigated as design parameters of posts. Theresults ofthis study showed that the stress on the remaining dentine only decreased slightly when the post diameter increased. Excessive post length might be harmful to the entire structure.