Abstract: For the misalignmentrubbing coupling fault rotorbearing system caused by misaligned bearing， mechanical and finite element models of dualdisk misalignmentrubbing coupling fault rotorbearing system were established. The equivalent misalignment moment and contact theory were used to study the effect of rotational speed on the dynamics characteristics with the nonlinear finite element method. The results showed that the misalignmentrubbing coupling fault mainly embodied in the rubbing fault， and the frequencydoubled appeared early with the peak increased rapidly. The fault signal was further divided to same width parts with the wavelet basis function， and the change trend of the double frequency peak showed that the double frequency ratio value is a judgment basis for the fault degree of the rotor system containing misalignment fault.

Key words: misaligned bearing, rubbing, dualdisk rotor, coupling fault, fault band