Objective Finite element analysis was used to study the stress distribution and biomechanical stability of the combined Long locking plate and the new Short locking plate in the treatment of Sanders IIa, Sanders IIb and IIIab calcaneal fractures, providing theoretical basis for clinical work. Method Volunteers CT data through Mimics different software, such as establishing Sanders type IIa, IIb and calcaneal fractures IIIab type 3 d model, after the bar sectional steel plate internal fixation material attribute assignment, at the same time simulation with bone in the neutral position and force of the back stretch when 20°, the reference specimens of human physical shape, put 500N vertical axial load, application analysis of fracture under the action of a force displacement, relative displacement of bone tissue and force of the internal fixation, and so on, analysis and comparison under the bar plate fixation combined the stability of the different types of calcaneal fractures. Result In the fixation of calcaneal fractures of type Sanders IIa and type Sanders IIb with long and short combined locking plates, the stress concentration positions of the plates and calcaneal fractures were basically the same. The maximum stress difference between the two plates in the fixation of calcaneal fractures of the same type was less than 5MPa, and there was no significant difference in the maximum displacement of the fracture model.In the fixation of calcaneal fractures of type Sanders IIa and Sanders IIb with long and short combined locking plates, the maximum stress concentration of forearm plate screws is associated with the risk of metal fatigue. The maximum stress difference is up to 12MPa, and the maximum calcaneal displacement is up to 9μm. Conclusion Long combined type locking plate and short combined treatment Sanders, a locking plate type IIa and Sanders type IIb calcaneal fractures has no obvious difference, and Sanders IIIab model in the treatment of calcaneal fractures, long combined effect of locking plate fixation is better than the short type combined locking plate, but the final experiment results need further by biomechanics and clinical research.