Objective To study the distribution of fragment displacement, plate and screw stress in different internal fixation models of posterolateral tibial plateau fractures under static axial load, and to explore the best internal fixation and surgical approach in accordance with mechanical principles. Methods The models of posterolateral tibial plateau fractures were established by finite element software, and the finite element models of three kinds of plate fixation methods for lateral tibial plateau fractures were established respectively. The posterolateral fragment displacement and stress distribution of the tibial plateau and the stress distribution of the plate and screw under the three fixation methods of the posterolateral tibial plateau fracture were simulated under the condition of 60 kg jogging (1200 N). Results A three-dimensional finite element model of the plate fixation for posterolateral tibial plateau fractures was constructed in the finite element software. The axial displacement of the horizontal belt plate was close to the lateral anatomical plate and the posterior reconstructive supporting plate under 1200 N static axial force. With the stress increased, the overall displacement and maximum stress of each group were relatively close. Conclusion The finite element model of posterolateral tibial plateau fractures and model of plate internal fixation can effectively simulate the real situation of fractures. posterolateral tibial plateau fractures with the horizontal belt plate fixation can achieve similar biomechanical effect as posterior reconstruction plate fixation or lateral anatomical plate. The use of horizontal belt plate fixation may reduce postoperative complications through a more minimally invasive incision.