An Ethernet power supply receives a DC voltage through a bus positive terminal and a bus negative terminal, and is coupled to a load device. The Ethernet power supply includes a first control module and a second control module. The first control module provides a first control signal through the bus negative terminal to confirm whether the load device is a valid load. The second control module is used to connect or disconnect a coupling relationship between the bus positive terminal and the first control module according to whether the load device is connected to the Ethernet power supply.