<p>Lubrication failure of the port plate pair in radial piston pumps is a key bottleneck restricting service life under dynamic load and high-pressure conditions. The paper establishes a thermoelastohydrodynamic (TEHL) model for the port plate pair, which incorporates bidirectional coupling between hydrodynamic-hydrostatic pressure fields and heat conduction-elastic deformation. Driven by a dynamically varying sinusoidal load, the model simultaneously solves for the oil film pressure, temperature field, and thermoelastic deformation. The results reveal that over 97.5 % of the load is supported by static pressure, with hydrodynamic pressure contributing only a minor dynamic adjustment within ±2.5 %. The simulation results show an average deviation of ≤ 15 % from ring-on-block friction and wear test data. When the operating pressure increases from 16 MPa to 42 MPa, the peak oil film thickness remains stable at 46.2 µm, while the maximum thermoelastic deformation reaches 6.4 µm and the oil film temperature rises by 12 K. This confirms the significant role of thermal effects under high pressure. A key parameter optimization analysis indicates that a rotational speed of 800–1000 r/min, an initial clearance of 40–42 µm, a radial load of 10–30 kN, and a sealing land width of 37.5 mm collectively yield the most favorable compromise between minimized thermoelastic deformation and maintained oil film thickness. This study provides precise theoretical support for the wear-resistant design of radial piston pumps under extreme operating conditions.</p>