Abstract: Anon-Newtonian thermal elastohydrodynamic lubric ation model is set up to analyze running-in process under heavy load.The equiv alent viscosity method is used to account for the visco-plastic characteristics of non-Newtonian fluid. Thenumerical solutions are presented. The results sho w that the friction coefficient of thermal EHL solutions is much lower thanthat of the isothermal one. However, the temperature rise of thermal EHL solution u nder heavy load is irrationally high. Whenthe rheological effect of non-Newton ian fluid is considered, the temperature rise drops to reasonable level and the frictioncoefficient is relatively comparable to the tested counterpart.