The working performance and stability of the axial piston motor are significantly affected by the frictional lubrication characteristics of the valve-plate pair． Considering the oil film pressure distribution and moment action of the auxiliary support belt with surface veins，this study established the oil film dynamic model of the valve-plate pair，and analyzed the change rules of the flow leakage and friction loss of the valve-plate pair under different working pressure，working speed and swash plate angle． The research results show that the leakage flow of the valveplate pair of the axial piston motor increases approximately linearly with the increase of speed，and the increase rate decreases with the increase of pressure． At the same time，the viscous-friction torque of oil film increases with the increase of the rotational speed and pressure，and there is an approximate linear relationship between the friction torque and the rotating speed． The leakage flow and the thickness of the central film decrease with the increase of the inclined angle of the swash plate，while the friction torque increases with the increase of the inclined angle．