A power delivery device and a control method are shown. The power delivery device includes a power conversion circuit, a power factor correction circuit, and an output voltage control circuit. The power conversion circuit includes a primary side and a secondary side, and is configured to receive an input voltage and convert the input voltage to an output voltage. The power factor correction circuit is electrically coupled to the primary side and configured to increase the power factor of the power delivery device. The output voltage control circuit is electrically coupled to the secondary side and configured to control the voltage level of the output voltage. When the voltage level of the output voltage is lower than a predetermined level, the power factor correction circuit is deactivated.