Ultrahigh-voltage cylinder power-off protection device

The utility model relates to the technical field of ultrahigh pressure equipment, in particular to an ultrahigh pressure cylinder power-off protection device which comprises a valve body and an equipment cylinder which are sequentially arranged from left to right. A pressure relief valve is arranged on a pressure relief pipe of an ultrahigh pressure cylinder pressure relief plug, the pressure relief valve is sequentially provided with a valve body and an equipment cylinder from left to right, a piston is arranged in the equipment cylinder in a sliding mode, an iron ring is arranged at the left end of the piston, and when an electromagnetic iron ring on the inner wall of the left side of the equipment cylinder is powered on, the iron ring can be attracted to be attached to the electromagnetic iron ring; when the ultrahigh pressure equipment is powered off, the electromagnet ring is powered off and loses the adsorption force to the iron ring, the tension spring pulls the piston to the right end of the equipment