A multi-phase converter has a plurality of switching circuits coupled in parallel and a control circuit. The control circuit provides a set signal to successively turn ON the switching circuits under power operation based on an output voltage, a reference signal and a nonlinear control signal. When a number of switching circuits under power operation decreases, the nonlinear control signal increases to a preset value from an initial value, and then the nonlinear control signal decreases to the initial value with a preset slew rate.