The problem of nonlinear rigid rotor system with pedestal looseness fault was studied. The dynamic pedestal looseness fault models of the rotorsliding bearing system with nonlinear rigid under an unsteady oilfilm force were constructed , which took into account the material nonlinear factors. The characteristics on timing diagrams, spectrogram plots and shift centerline orbits were given about the response following the change of system parameters, by using the RungeKutta numerical value integral method. In the end, the feasibility of the theoretical simulation was verified by the diagrams from the test. The characteristics analysis may help to diagnose and identify the fault in rotor system.