The invention discloses a bolt looseness preventing structure for connection of steel-structure members. The bolt looseness preventing structure is used for connection of the two steel-structure steel members with the ends being stacked up and down. The bolt looseness preventing structure mainly comprises a bolt and a nut. An upper through hole and a lower through hole are coaxially formed in the connecting ends of the two steel-structure members correspondingly, a screw of the bolt penetrates through the upper through hole and the lower through hole from bottom to top, and the head of the bolt is located on the lower surface of the lower steel-structure member; and meanwhile, the end, close to the head, of the screw of the bolt is fixed into the lower through hole through plug welding, and the end, away from the head, of the screw of the bolt is fixed to the upper surface of the upper steel-structure member through the nut. The bolt looseness preventing structure has the advantages that through the bolt looseness preventing design structure for connection of the steel-structure members, the problem that the screw drives the nut to rotate under the power load effect, and consequentially the bolt used for connection of the steel-structure members gets loose can be effectively solved, and the connection safety of the steel-structure members is ensured.