Abstract: The basic configuration and working principle of an innovative three-pole AC(alternating current) magnetic bearing are introduced.Using equivalent magnetic circuit method,the mathematical model of the suspension forces is deduced.Aiming at the coupling identity of the mathematical model of the three-pole AC magnetic bearing in two-phase static coordinates,a pseudo-linear model is given based on the inverse system method.In order to avoid the system performance deterioration due to the model error and the external disturbance,the internal model control method is applied to synthesizing the pseudo linear system.The simulation experiments show that this kind of decoupling control strategy can realize dynamic decoupling control between radial displacements of the three-pole AC magnetic bearing,the rotor can be suspended steadily and the whole control system has good dynamic and static performance and good robustness.