Abstract: In order to explore the dynamic characteristics of the circumferential rod fastening rotor-bearing system, a numerical model of three-dimensional Gaussian random rough surface was established by using the method of autocorrelation function. Moreover, the geometric model of rough surface was generated by Ansys APDL. Abaqus software was used to simulate the contact of rough surface, and the contact stiffness of rough surface under different preloads was obtained. The finite element model of the circumferential rod fastening rotor-bearing system of a certain type of gas turbine considering the contact stiffness was also established. The dynamic characteristics of the system with different preloads and clearances of bearing assembly were calculated. It is shown that critical speed of rotor-bearing system increases nonlinearly with the increase of preload, and the amplitude of unbalance response increases with the increase of preload and clearance of bearing assembly as the rotor has passed the critical speed.