A multi-phase DC-DC converter is provided. A plurality of switching sets are coupled to an output, wherein each switching set includes a phase node. A plurality of inductors are separately coupled between the phase nodes and the output. A sense circuit has a plurality of sense units separately coupled to the phase nodes, each sensing a signal from the corresponding phase node and generating a sensing signal. A PWM generator includes a plurality of subtracting units, each subtracting a first signal from one of the sensing signals to generate a difference signal, wherein the first signal is generated by summing each of the sensing signals divided by a predetermined value except for the one of the sensing signals. The PWM generator generates a plurality of PWM signals to balance the currents of the inductors according to the difference signals.