Abstract: A coupled model was setup to analyze rotor thermal stability due to rub. Thermal bow equation and rotor vibration equation were coupled together considering the bow induced by thermal impact as an additional unbalance force. Eigenvalues of the coupled equations were calculated to analyze the rotor stability during rub. The change law of eigenvalues with rotating speed and seal stiffness was deduced. It was found that the rub-induced vibration is unstable if the rotor runs below its critical speed; real part of eigenvalues increases with the increase in seal stiffness; spiral period of thermal bow decreases with the increase of seal stiffness. Rub induced vibration is stable if the rotor＇s runs above its critical speed in case of light rub; however, at severe rub case, the vibration is always unstable despite that the rofors operation speed is above its critical speed or not.