Power supply monitoring system and control method and equipment

The invention discloses a power supply monitoring system, a control method and equipment. The system comprises a controller ECU, an engine control ECM, an electronic monitor, a vehicle-mounted terminal, a storage battery, a power supply main switch and a key switch. Wherein the controller ECU is connected with the engine ECM, the electronic monitor and the vehicle-mounted terminal bus; the power supply main switch is electrically connected with the controller ECU, the engine ECM, the electronic monitor and the key switch; and the storage battery is electrically connected with the vehicle-mounted terminal and the power supply main switch. When a user finishes using the machine, a system power supply is turned off, but the vehicle-mounted terminal is normally electrified, an engine ECM and other parts can be electrified after a power supply main switch is electrified, the system judges within a certain time, and the vehicle-mounted terminal detects the state of the electrified parts. When the main power supply