To demonstrate the support characteristics of active magnetic bearing( AMB), the equivalent stiffness and the equivalent damping are the commonly used parameters,which are inherited from the stiffness and damping parameters in traditional mechanical bearings. The support characteristics of AMB are determined by its transfer function of control system. Therefore, it is relatively difficult to confirm the equivalent stiffness and equivalent damping of AMB. In addition, the experiment methods for measuring the equivalent stiffness and damping of AMB proposed by most recent papers are almost all based on the single degree of freedom( DOF) model, which can not be applied practically to the multi-DOF AMB-rotor systems. In this study, the applicable conditions for applying the equivalent stiffness and damping in AMB are firstly illuminated by analyzing the difference and relation between the traditional mechanical bearings and AMBs. Then, a method for measuring the equivalent stiffness and damping for the multi-DOF AMB-rotor systems is proposed. The experiments indicate the proposed method can identify the equivalent stiffness and damping of AMB-rotor system correctly and factually, showing its significance in the analysis and design of the AMB characteristics.