The utility model provides an apply device of screwing up moment for pneumatic quick -witted rotor shaft of low temperature hydrogen, includes key axle and main shaft, and key axle one end has the parallel key, and during the rotor shaft keyway can be packed into to the parallel key, the main shaft was an axle that has the hexagonal, after the assembly was accomplished, the axial region of key axle and main shaft divided the formation fixed axle, and the external diameter and the rotor shaft bore diameter of this fixed axle equal. Exert when tightening moment, by the hexagonal position of the fixed main shaft of spanner, has fixed pneumatic quick -witted rotor shaft promptly, use the moment spanner as rotor shaft both ends nut exert tighten moment can. The utility model discloses can apply and screw up moment for the various axles that have the keyway in long and thin hole and the hole that have.