Considering the magnitude of elastic deformation was the same as the film thickness of port plate pair under high pressure, the model of lubrication was established by the theory of elastohydrodynamic lubrication. The influence of elastic deformation on lubricating characteristics was analyzed using finite difference method. The results showed that the average film thickness increased by 14.48%, but the largest film pressure decreased by 18.6% in the elastic case. And the film load capacity and leakage increase obviously, but frictional torque decreases obviously in the condition of small film thickness. By contraries, the influence of elastic deformation on lubricating characteristics could be neglected in the condition of large film thickness beyond the film thickness 15 μm. The study lays a foundation for design and research on port plate pair of high-pressure axial piston pump.