Dynamic model of nonlinear rigidity-rotor system with rubbing fault was set up by taking the linear and cube items as the physically nonlinear factors. The nonlinear dynamic behaviors of the system caused by rubbing fault were investigated with numerical integral and Poincare mapping methods. The bifurcation diagram and maximal Lyapunov exponent curves of the response were given following the changed frequency ratio. Some typical Poincar6 maps, phase plane portraits, time-history, trajectory of journal centers and amplitude spectra etc. were also proposed to show the period-doubling, quasi-periodic and chaos behaviors in the rotor system.