By combining the thermal elastohydrodynamic lubrication theory, thermoelastic mechanics theory and principle of heat-pressure conversion, a method was presented to solve the material thermal expansion coefficient of solid surface in the thermal elastohydrodynamic lubrication of line contact. It could solve the thermal elastic deformation of solid surface caused by non-uniform temperature field under constraint of oil film pressure. Numerical results satisfying the convergence conditions were obtained by an example, and the influence of load, entrainment speed and solid material on the material thermal expansion coefficient were further studied. When the two solids are the same metal material, the results show that the thermal expansion coefficient of the solid surface with large radius is relatively large at each point in the computational domain; when the load increases, the material thermal expansion coefficient of the solid surface at each point becomes larger; when the entrainment speed increases, the thermal expansion coefficient will decrease; when the density of solid increases, the material thermal expansion coefficient decreases.