A multi-phase DC-DC controller. The multi-phase DC-DC controller comprises converter channels, a channel control device and a power control device. Each converter channel comprises a switch device, a first output node and an inductor coupled between the switch device and the first output node. The channel control device generates adjusted pulse width modulation signals according to control signals of the converter channels to respectively control operation of the switch device in each converter channel. The power control device generates the control signals according to sensed currents in the converter channels so as to dynamically turn on or off each converter channel according to the sensed currents.