The invention discloses an electric power system power distribution protection device, an application and a method. The electric power system power distribution protection device comprises a power distribution cabinet body, a travel switch, three electromagnetic relays, a signal lamp and a controlled switch, wherein the three electromagnetic relays act on the controlled switch through the signal lamp, electromagnetic coil circuits of two of the electromagnetic relays are mutually controlled and respectively act in normal power supply and temporary maintenance, the other electromagnetic relay performs delay timing, assists standby application and is also controlled by the other two electromagnetic relays, and the three electromagnetic relays form three control circuits to act on the controlled switch. The electric power system power distribution protection device can perform operations such as maintenance, transformation, switching and periodic inspection on power distribution equipment in a power distribution cabinet or box without interrupting power supply; when the power distribution cabinet or box is illegally opened by a law breaker, power supply for the system is interrupted if a special key is still not inserted within a set time, and the power supply is recovered only when the special key is inserted.