This disclosure discloses a power supply method and a power supply device, and pertains to the field of power supply technologies. The method includes: supplying, by a power supply device, power to a load through a power supply port, where the power supply port is connected to a power receiving port of the load by using a power supply cable; and communicating, by the power supply device, with the load through a communications port, to manage a behavior of obtaining power by the load from the power supply device, where the communications port is connected to a communications port of the load by using a communications cable. In this disclosure, the power supply device is a power supply of the load and a controller of the load.