A power module includes a power conversion circuit, a fan, a controlling unit, a capacitor, a current-adjusting element and a soft start controlling unit. The power conversion circuit is used for outputting a DC voltage. The fan is connected with the power conversion circuit. The controlling unit is used for issuing a control signal to the fan, thereby controlling operation of the fan. The capacitor is connected with the fan in parallel. The current-adjusting element is connected with the capacitor in series for adjusting the magnitude of current flowing through the capacitor. The soft start controlling unit is connected with the current-adjusting element. When the power module is connected with a connector of a power supply system, the soft start controlling unit controls the magnitude of current flowing through the current-adjusting element to be gradually increased, so that the magnitude of current flowing through the capacitor is gradually increased.