A power control apparatus with dynamical adjustment of driving capability for converting an input power into an output power includes a transformer, a switch transistor connected to the transformer, a pulsed width modulation (PWM) driving controller generating a PWM signal and connected to the switch transistor, an isolation element, an output diode and an output capacitor. The first side coil of the transformer and the switch transistor are connected to the input power, the second side coil of the transformer is connected to the output diode and further connected to the output capacitor and an external load. The isolation element converts the output power into a feedback signal providing the PWM driving controller to dynamically control the PWM driving signal through adjustment so as to implement the optimal turn-on current for the switch transistor. Therefore, electrical performance and conversion efficiency are greatly improved by reducing the switching loss.