Objective To investigate the effects of three-dimensional (3D) screws and circular plates on the biomechanical stability of Sanders ABⅢ calcaneal fractures. Methods Calcaneal computed tomography (CT) and magnetic resonance imaging (MRI) data from a 26-year-old volunteer were collected to establish a 3D finite element model of a Sanders IIIAB calcaneal fracture fixed with 3D screws and circular plates. A longitudinal load of 700 N was applied to compare the variations in the stress, displacement of the bone block, and internal fixation in the different models. Results Under 700 N longitudinal loads, the maximum displacement of the bone block and the maximum stress of the bone block and internal fixation were concentrated at the intersection of the posterior talar articular plane internal fixation and fracture line. The overall displacements of the bone blocks in the 3D screw and circular plate models were similar. Compared with the circular plate model, the maximum and average stresses of the bone block and internal fixation in the 3D screw model were lower, and the displacement and stress changes of the 3D screw model were closer to those of the complete calcaneal bone model. Conclusions In the fixation of Sanders IIIAB calcaneal fractures, both 3D screw and circular plate fixation methods can provide good stability. The biomechanical properties of the 3D screws were better than those of the circular plates, which is consistent with the biomechanical characteristics.