In order to solve problems of performance prediction considering thermoelastic deformation and size effect of large heavy thrust bearing, the performance variation of thrust bearing with extreme loads and sizes was studied through thermoelastohydrodynamic calculation of thrust bearing. The thermoelastohydrodynamic model basic equations of tilting pad thrust bearing were introduced. The bearing performance data under different size and specific pressure were obtained, and the size effect of large heavy thrust bearing was discussed. The results show that, the maximum film pressure should stay away from the tile tip, and close to the fulcrum. This helps to make the pressure uniform distribution and improve the bearing capacity. Due to the impact of the deformation, when the load exceeds a certain limit values, large heavy bearing performance will increase violently as the load changes slightly, even lead to burnt failure. To avoid this phenomenon, the maximum allowable specific pressure of thrust bearing should be checked, and the design of elastic support or balance beam for heavy load bearings is needed.