Objective To observe the stress distribution of mandibular angle fracture under different rigid internal fixation(RIF) methods by developing a three-dimensional finite-element method(3-D FEM).Methods CT scan technology and related software were used to develop a 3-D FEM of mandibular angle fracture under different RIF.On this basis,the mandibular stress distributions were analyzed by MSC.Marc software.Results The von Mises stress mainly concentrated on the middle of the titanium plate in tension band fixation,while in two mini-plate fixation,it concentrated on the middle of the superior titanium plate.In the tension band fixation,the max-values of displacement was more than that in the two mini-plate fixation.When the biting force dropped to 102.7 N(LMOL) and 40.3 N(ICP),the furthest fracture mobility got into margin of safety under the tension band fixation.Conclusion The two mini-plate fixation was more stable than the tension band fixation.Choosing the suitable occlusion,tension band fixation could also provide sufficient stability for the mandibular angle fracture.