The utility model relates to a technical field is measured to nuclear power plant's nuclear, specifically discloses a source range HN of nuclear instrument system of nuclear power plant connects moment fastening tool. A source range HN of nuclear instrument system of nuclear power plant connects moment fastening tool, this fastening tool of includes sleeve and jackscrew, and wherein, the sleeve is whole to be equipped with the jackscrew for the size assorted cylindrical structure of department of the cable joint with treating the fastening on sleeve one end lateral wall, and messenger's sleeve keeps relatively fixed with the cable joint who treats the fastening, and the sleeve other end is equipped with draw -in groove, its and outside moment spanner phase -match. A source range HN of nuclear instrument system of nuclear power plant connects moment fastening tool can control the penetration piece cable joint's of system pretightning force, and do not receive the constrictive restriction in space, shorten this operating time by a wide margin.