Provided is a device, cabinet, and method for preventing power outage of an entire cabinet, applied to each node in the cabinet. The device comprises a diode (101) and a first protection circuit (102). The anode of the diode (101) is grounded (GND), and the cathode is connected to an external voltage supply copper busbar via the first protection circuit (102) and connected in parallel with an external node. The first protection circuit (102) is configured to monitor a current value of the diode (101), and disconnect a connection line between the corresponding diode (101) and the voltage supply copper busbar when the current value exceeds a preset fusing-current threshold. The diode (101) is connected in series with a fuse, such that the fuse blows when the diode (101) is short-circuited, so as to effectively prevent a voltage on the power supply copper busbar from being pulled down, such that the power supply copper busbar can continue to supply power to other nodes, thereby effectively improving the power supply reliability of a cabinet server.