<p>This study established a “temperature–pressure-deformation” coupled research framework to analyze the lubrication characteristics of double rectangular cavity hydrostatic thrust bearings under extreme working conditions. Firstly, the relationship between lubricating oil viscosity and temperature was considered. Subsequently, the impacts on the oil film temperature field, pressure field, and deformation of friction pairs were investigated from theoretical, simulation, and experimental perspectives. The Clearance oil film was extracted through three-dimensional modeling of the double rectangular cavity hydrostatic thrust bearing structure. The variation patterns of the oil film pressure field and temperature field were subsequently analyzed using fluid simulation under extreme working conditions. At the same time, the deformation of the friction pair and the changes in the thickness of the oil film were analyzed through numerical simulation. The results indicate that load and rotational speed are the primary factors influencing the alteration of the increase in oil film pressure and the rise in oil film temperature, respectively. Moreover, the numerical simulation data are in complete agreement with the experimental results. In addition, under extreme working conditions, the deformation of the friction pair caused by increased pressure and temperature does not lead to dry friction in the bearing. These research findings provide a theoretical foundation for the stable operation of double rectangular cavity hydrostatic thrust bearings under extreme working conditions.</p>