The present invention discloses a multi-phase power supply dynamic response control circuit and a control method. When a rapid rise of the load is detected, an output PWM signal is temporarily adjusted to enter a second operation mode from a first operation mode to supplement energy to the load and prevent the output voltage from decreasing. The present invention requires little modification to the existing circuit, and adopts simple, explicit and efficient detection method, realizing rapid dynamic response by providing sufficient energy for the load when the load current is suddenly increased.