<p>A novel parameter identification method for magnetic levitation bearing rotor systems is proposed, based on the modulation function method. The fundamental principle of the modulation function method for parameter identification is derived on the basis of the characteristics of the modulation function. The transformation of the differential equation model of a continuous system into a general algebraic equation model is effectively achieved, thereby avoiding the influence of errors introduced by the initial value and differential derivation of the system. Modulation function method parameter identification models have been established for single-degree-of-freedom and multi-degree-of-freedom magnetic levitation bearing rotor systems. The influence of different parameters of Hartley modulation function on the accuracy of system parameter identification has been investigated, thus providing a basis for the design of Hartley modulation function parameters. Simulation and experimental results demonstrate that the modulation function method can effectively identify system parameters despite the presence of system noise.</p>