A control method for improving dynamic response of switch power is based on a closed-loop control system comprising a sampling module, a dynamic control module, an error calculation module, a PID module, a mode control module, and a PWM module. The sampling module samples an output voltage Vo, and the dynamic control module compares the output voltage Vo with a set maximum voltage Vomax, a set minimum voltage Vomin, and a reference voltage Vref, so as to determine whether to adopt a dynamic mode. In the dynamic mode, when the output voltage Vo changes greatly, the output voltage Vo is rapidly restored to a stable voltage by inputting large power or small power.