The invention discloses a protection plug with a power-off tripping function. The protection plug comprises an amplifying circuit, a release, a rectifying circuit, a power indicator circuit, a step-down circuit, a thyristor, a zero sequence current transformer, a ground wire current transformer and an open-phase protection circuit. The invention provides a novel leakage protection device. The novel leakage protection device has an open-phase protection function, namely cutting off load power supply when L- or N-end power supply is interrupted or the contact is poor, an over-voltage protection function, namely cutting off the load power supply by a protector in an electrified state when a power supply voltage exceeds 280V+/-10V, and a plug over-temperature protection function, namely cutting off a power supply when the temperature of a protector plug reaches a preset temperature.