The invention relates to an active power adjusting device which comprises a first group of power electronic switch element series circuits, a second group of power electronic switch element series circuits and a third group of power electronic switch element series circuits. The active power adjusting device utilizes one of the second group of power electronic switch element series circuits and the third group of power electronic switch element series circuits to carry out high-frequency switching when power supply voltage is changed, other two groups of power electronic switch element seriescircuits are utilized to carry out low-frequency switching. Therefore, the active power adjusting device can maintain the voltage stability of the two end points of a load and does not need to arrangea DC capacitor to stabilize DC voltage.