The FEM was employed to establish a nonlinear dynamical model of a rotor-bearing experimental system. The fixed interface mode synthesis dimension reduction method was adopted to to save the computing time.The Newmark-β method was employed to solve the reduced model numerically. And the three-dimensional spectrogram, bifurcation diagram, three-dimensional amplitude diagram, chart of axis trajectory, etc were used to analyze the nonlinear characteristic of the dynamic system comparing with those results of the experimental system. Results show that the numerical dynamic model can accurately reflect the characteristics of the nonlinear experimental system. So, it is very important practical significance to apply FEM and dimensional reduction theory into the research of the local nonlinear rotor system, which can provide more accurate verification and reference for the advanced nonlinear dynamic design of the complex rotor system.