The utility model relates to the field of pipe gallery equipment. The utility model relates to a stiffening device, in particular to an anti-loosening screw stiffening device. The connecting device comprises a bolt and a square nut connected with the bolt in a screwed mode. The apparatus also includes: a processor; the limiting piece comprises an abutting part arranged on the bolt in a sliding andsleeving mode and a limiting part connected with the abutting part. Wherein the abutting portion is arranged between the square nut and the bolt head portion, the limiting portion extends downwards to the side portion of the direction nut and abuts against the side portion of the square nut, and the limiting portion stops the rotating trend of the abutting portion relative to the locking nut. Locking nut, the screw is screwed with the bolt; the nut is arranged between the sliding section and the square nut; due to the fact that the limiting piece abuts against the end of the bolt, relative rotation of the end of the bolt and the square nut is prevented, looseness between the bolt and the main hoisting screw can be effectively prevented, stability of connection between the main hoisting screw and the channel steel is effectively guaranteed, and the problems existing in the prior art are solved.