BACKGROUND: Tibial plateau fractures (TPFs) are a challenging type of fracture in orthopedic traumatology. We previously designed a plate (Patent Number: CN201520195596.5) for posterolateral TPF combined with posterior lateral collapse.. In this study, finite element analysis was used to compare the biomechanical characteristics of two internal fixation methods for posterolateral TPF. We investigated the support effect of the new steel plate on lateral TPFs combined with posterior TPFs. METHODS: Two models of complex TPF were established. Model A was fixed with the new type of plate, and model B was fixed without the plate. Three axial loads of 500, 1,000, and 1,500 N were applied using FEA on the two fracture models (A and B) to analyze the data. RESULTS: In model A, the maximum displacement at 500, 1,000, and 1,500 N was 0.085797, 0.17043, and 0.25465 mm, respectively; the maximum stress of the bone block was 11.285, 20.648, and 29.227 MPa, respectively; and the maximum strain of the bone block was 0.0012474, 0.007435, and 0.0035769 mm, respectively. The maximum displacement of the internal fixation was 0.096932, 0.18682, and 0.27655 mm, respectively; the maximum stress was 69.54, 112.1, and 155.71 MPa, respectively; and the maximum strain was 0.00066228, 0.0010676, and 0.0014829 mm, respectively. In model B, the maximum displacement of fractures at 500, 1,000, and 1,500 N was 0.15675, 0.29868, and 0.44017 mm, respectively; the maximum stress of the bone block was 6.5519, 12.575, and 18.842 MPa, respectively; and the maximum strain of the bone block was 0.0032554, 0.0074357, and 0.012146 mm, respectively. The maximum displacement of the screw was 0.14177, 0.27109, and 0.39849 mm, respectively; the maximum stress was 48.916, 92.251, and 135.27 MPa, respectively; and the maximum strain was 0.00046608, 0.00087893, and 0.0012887 mm, respectively. CONCLUSIONS: The fixation method using this type of plates and screws can replace other methods using two plates to fix complex TPF.