The utility model discloses a protector is emptyd to nuclear power station pressure vessel's bolt for protect when toppling over behind the bite bolt to on the cutting nuclear power station pressure vessel flange face or many, include: be used for connecting respectively waiting to cut bolt and auxiliary stay bolt, and can limit and wait to cut the bolt for the installation support bracket of auxiliary stay bolt in a certain side's rebound, be used for providing jacking power for waiting that it cuts off in the twinkling of an eye to cut the bolt, cutting the hoisting device of one section promotion that makes progress of bolt with continuous the waiting of installation support bracket, hoisting device sets up on the installation support bracket, wherein: the regulation and lifting device makes its produce pretightning force, cuts off and waits to cut the bolt, and hoisting device drives the one section upwards separation of waiting to cut the bolt with the installation support bracket links to each other after the cutting. Implement the utility model discloses a protector is emptyd to nuclear power station pressure vessel's bolt keeps its vertical position in the time of can cutting off at the bolt on the nuclear power station pressure vessel, can effectively avoid the problem that the bolt falls or appear empting at the breaking moment downwards.