Abstract: The dynamics model of a rigid asymmetric active magnetic bearing rotor system with five degree of freedom is established and the identification equation of the dynamic coefficients deduced accordingly, while the identification parameters are obtained by means of multi frequency excitation method. The results based on the established model as compared with the theoretical computed ones show that the identification model of the dynamic coefficients of the system and the corresponding method are valid and applicable. The coefficients of force stiffness and force electric current are the same along the x and y axles for the axial bearing system, while they are a little bit larger than the corresponding coefficients of the thrust bearing system. There exists a coupling effect between the axial magnetic bearing and the rotor with horizontal vibration, this has great effect on the system stability, thus the coupling effect is ineligible in design of the system.