Abstract: Considering the transient three-dimensional temperature field of the film and bearing bush, the transient thermal-responses of rotor-bearing system to mass unbalance are performed. The tracks and thermal-responses obtained by considering two-dimensional temperature are compared with the tracks obtained by considering three-dimensional temperature. The results show that the rise of temperature must be considered in the analysis of the stability of high-speed rotor-bearing system. The transient three-dimensional temperature must be considered when analyzing the stability of rotor-bearing.