Objective To investigate the differences in biomechanical properties of 3 internal fixation patterns(the lateral plate and screw group, the rear plate and screw group, and the front and rear lag screw group) for treating posterolateral tibial plateau fracture under different axial loads. Methods Based on CT data of the tibial plateau, the entity model of 1/2 and 1/4 posterolateral tibial plateau fracture with 3 internal fixations were established and meshed to analyze force status of the fracture models with 3 internal fixations under different axial loads. ResultsUnder the axial load of 1 kN, for the 1/2 posterolateral tibial plateau fracture model, the displacements of the fracture fragments in the lateral plate and screw group, the rear plate and screw group, and the front and rear lag screw were 552.082, 67.964, 54.085 μm, respectively, and the stresses on the fixation device were 306.745, 231.844, 73.047 MPa, respectively. For the 1/4 posterolateral tibial plateau fracture model, the displacements in the three groups above were 416.072, 302.107, 150.639 μm, respectively, and the stresses on the fixation device were 306.673, 208.467, 73.607 MPa, respectively. Both the displacements of the fracture fragments and the stresses on the fixation device increased correspondingly under the axial load of 1.5 kN, and the trend of the data was similar to that under the axial load of 1 kN. Conclusions The results from the fracture models with 3 internal fixation patterns show that the front and rear lag screw group has a superior biomechanical stability under two different axial loads, and the similar mechanical properties can be achieved in the rear plate and screw group. Therefore, the front and rear lag screws will be preferred to treat posterolateral tibial plateau fracture with less obvious displacement in clinic.