The simulation model of the rotor is obtained through finite-element-method, and the dynamic models of components of active magnetic bearing(AMB) are built. Then, the state-space model of AMB-rotor system is constructed. With this state-space model, the frequency domain responses of force transfer rate at the locations of bearings under disturbance are calculated, and the impulse responses of the rotor vibration and dynamic bearing force are simulated too. The vibration transmission characteristics of AMB are studied and compared to rolling-ball bearings. It is shown that, with the ability of active control, the AMBs behave quite differently from rolling-ball bearings. The frequency domain response of force transfer rate is quite flat, avoiding sharp peaks around some frequencies along with the roll-ball bearings. With AMBs, the impulse responses of rotor vibration and dynamic bearing force return to stable level sooner than with rolling-ball bearings, and the vibration transmission is reduced.