Abstract： Objective To construct a rational and exact three - dimensional finite element model of the first permanent mandibular molar. Methods The first permanent mandibular molar was scanned by CT and the images were processed by softwares such as PhotoShop. Then special software SolidWorks2010 was used to establish a three - dimensional finite element model . Results A three - dinensional finite element model of the first permanent mandibular molar was established, including enamel, dentin, pulp, alveolar bone and periodontium. Conclusion The modeling method is effective and reliable. The three- dimensional finite element model has favorite similarities in geometry and biomechanics . It' s a simple and precise method for dentists to establish finite element models .