The thermal effect on a liquid film of uniform thickness on a rotating disk is analyzed by numerical method. The Navier-Stokes equations and the energy conservation equation in self-similar form for a case in which the disk temperature remains constant and equal neither the temperature of the surrounding gas nor that of the initial film, are solved by a finite-difference scheme. Assuming Newton's cooling law at the liquid-gas interface, the film thinning process was simulated for any Prandtl numbers. The numerical results reveal that if the Reynolds number is small and the product of Reynolds number and Prandtl number is up to unit order, the analytical expression in the lubrication limit gives a reasonable prediction for the transient film thickness. Furthermore, above calculations were extended by solving coupled equations for both liquid and gas phase with applicable boundary conditions, and the transient value of temperature and film thickness were obtained.