The present application provides a method for compensating harmonic currents using an active power filter. The method comprises the following steps: detecting a fifth harmonic and a seventh harmonic of a load current of a three-phase power network respectively; Generating a first command current value according to the fifth harmonic and the seventh harmonic; Harmonics of the load current are detected; Generating a second command current value according to the load current harmonics, the fifth harmonic and the seventh harmonic; adopting a current control closed loop to make the difference between the first output current and the first command current value within a preset range; adopting a current control closed loop to make the difference between the second output current and the second command current value within a preset range; Compensating low harmonics of the three-phase power network with the first output current and compensating high harmonics of the three-phase power network with the second output current. As with that various embodiment of the present application, the harmonic current compensation effect can be improved on the premise of reduce losses.