Abstract: FILE:8774USF.RTF20A computer main board on/off testing device, method and system. The testing device at least includes the hardware circuits of a command translation unit and a test procedure control unit. The hardware circuits are connected onto a standard interface of the computer main board so that the power switch and reset switch within the computer main board are connected by connection wires. The main board is switched and reset automatically by executing the program inside a test control unit. Codes issued from the main board are translated through a command translation unit. Working conditions during on/off switching, reset and power management suspend/wake up operations are assessed and results of the test are registered.