In order to study the influence of the surface morphology of the port plate on the lubrication characteristics of the port plate pair,the fractal theory was used to simulate the surface morphology of the port plate.The lubrication model of the port plate pair of the axial piston pump was established,and the model was solved by the finite difference method.The influence of the fractal parameters on the surface profile was discussed,and the effects of the fractal parameters and the working conditions of the port plate pair on the oil film bearing capacity,friction,friction torque and friction coefficient were analyzed.The results show that the larger the fractal dimension is,the higher the complexity of surface profile is,and the height of rough surface decreases with the decrease of scale coefficient; with the increase of cylinder inclination and speed,the oil film bearing capacity increases,but the friction,friction torque and friction coefficient also increase.There is a positive correlation between the lubrication performance of the port plate pair and the fractal dimension,and selecting a larger fractal dimension is conducive to improve the lubrication performance of the port plate pair.The smaller the scale coefficient,the smaller the friction,but the smaller the bearing capacity.Therefore,it is necessary to select a moderate scale coefficient.