A twentyfreedom nonlinear dynamic model was established for a two sp an dissymmetric elastic rotor system with rubimpact fault and oil film force. T he motion characteristic of the system was numerically studied and discussed wit h different parameters, and compared with the case without elastic bearing and t he experiment. The results indicate that the system has obvious chaos characteri stic, and different clearances and friction coefficients have marked influences on nonlinear characteristics of the system. The case considering elastic bearing has more serious nonlinear characteristics and more largescale chaos region t h an the case without elastic bearings. The elastic bearing must be considered in engineering practice. The results of experiment and numerical analysis are much identical, which prove the reliability of the numerical analysis.