Objective To establish a 3D finite element model of an anti-shearing force Ni-Ti memory shape alloy patella claw for fixing patellar fracture, and analyze its mechanical performance. Methods The internal fixation model of transverse patellar fracture by patella claw was established by Pro/E 5.0, and then imported it into ABAQUS 10.1 for finite element analysis on its mechanical properties. The mechanical performance and deformation of the patella claw under two different patella femoral joint forces FQ at the knee flexion angle of 30°, 60°, 90° were analyzed, respectively. Results Under the same boundary condition, with the respective FQ as 367.5 N and 3 675 N, the maximum displacements of deformation were different at different flexion angles. As compared to fixation by tension band, using patella claw was preferable, with stronger resistance to tension and more stable anti-shearing force. Conclusions Deformation and displacement of the patella claw are in accordance with the biomechanical results needed in clinic, and its stability can satisfy clinical requirements for functional exercise as early as possible.