Abstract: A power conversion circuit of a multi-phase power supply, a multi-phase power supply and a control method is provided. The power conversion circuit includes a PWM signal generating circuit, a driving circuit and a power circuit. The PWM signal generating circuit receives a counting code, generates a pulse width modulation signal when a count value characterized by the counting code is equal to their identification numbers, and controls on and off states of the switching transistor in the power circuit. Therefore, a plurality of phases of power conversion circuits in the multi-phase power supply may share one timing circuit to control on times of respective ones of the power conversion circuits, which is beneficial for reducing complexity and cost of the controller, and reducing circuit size and cost of the multi-phase power supply, and for implementation of a multi-phase power supply with higher phase numbers.