For the misalignment-rubbing coupling fault rotor-bearing system caused by misaligned bearing, the mechanical model and finite element model of dual-disk misalignment-rubbing coupling fault rotorbearing system are established, in which the impact of motor coupling is considered . The research of dynamics characteristics about the effect of rubbing stiffness and misaligned angle on the system is done with the equivalent misalignment moment, nonlinear finite element method and contact theory. Through the relevant research and analysis, it is found that the misalignment-rubbing coupling fault is mainly embodied in the rubbing fault. The frequency-doubled signal appears very early and its peak increases rapidly. This feature can be considered as a basis which can diagnose misalignment-rubbing coupling fault.