The invention discloses a power consumption control device, a magnetic levitation system and a power consumption control method thereof. The device comprises a voltage detecting circuit (10), a motorcontroller of the magnetic levitation system, a comparing unit, and a bearing controller of the magnetic levitation system; the voltage detecting circuit is used for detecting whether an input power source of the magnetic levitation system to be controlled is powered off; the motor controller of the magnetic levitation system is used for controlling a motor of the magnetic levitation system to operate as a generator in the case that the input power source is powered off; the comparing unit is used for detecting an operating parameter of the motor as the generator during operation, and comparing the operating parameter with a set parameter to obtain a comparison result; the bearing controller of the magnetic levitation system is used for adjusting a magnitude of a bearing bias current of the magnetic levitation system according to the comparison result, so as to control the power consumption of the magnetic levitation bearing of the magnetic levitation system within a set range. According to the scheme of the invention, the problem that the failure of motor energy feedback in the power-off energy feedback process affects the reliability of the magnetic levitation bearing system canbe solved, and the effect of improving the reliability is achieved.