The invention discloses a power-loss triggering device, including: a frame, an electromagnet and an impact bar; the impact bar vertically and movably penetrates through the frame; an energy storage piece is arranged and the energy storage piece may exert a downward action force on the impact bar; when the electromagnet is energized, the impact bar is positioned through electromagnetic force; when the electromagnet loses power, the impact bar loses a holding power from the electromagnet and conducts a downward impact movement under the action force of the energy storage piece. The power-loss triggering device is implemented through the electromagnet and an intermediate mechanism. In this invention, the electric current, the energy consumption and the cost of the electromagnet are reduced, the service life of the long-time energized electromagnet is prolonged.