A major factor affecting the life of an axial piston pump is the tribological behaviour of the slipper/swash plate friction pair. To disclose the slipper pair's time-varying lubrication process, a unique thermal-fluid-structure dynamic coupling model based on cumulative damage is developed. Viscosity-temperature-pressure effects, damage deformation, kinetic behaviour, and hydrodynamic lubrication are all thoroughly accounted for in this model. A broader time range of dynamic slipper lubrication state recognition allows for an effective evaluation of wear characteristics. The outcome shows that the classic lifespan under the rated pressure consists of three stages: Infant mortality stage, life cycle stage and the wear-out stage. Otherwise, only one stage with a high wear rate is shown.