The utility model discloses an adjusting device for balancing wire rope tensioning forces during the vault gas lifting process of a liquefied natural gas storage tank. The adjusting device comprises multiple sets of balancing devices; wherein each set of the balancing device comprises a first T-shaped bracket and a second T-shaped bracket that are mounted at the tank top, as well as a first guiding pulley and a second guiding pulley that are mounted at the vault; a first oil cylinder and a second oil cylinder are mounted at tank bottom bearing platforms of the storage tank respectively; the first T-shaped bracket, the second T-shaped bracket, the first guiding pulley, the second guiding pulley, the first oil cylinder and the second oil cylinder are positioned on the same vertical plane; the first T-shaped bracket, the first guiding pulley and the first oil cylinder are positioned on the same side, and the second T-shaped bracket, the second guiding pulley and the second oil cylinder are positioned on the other side; one end of a first wire rope is connected with a first oil cylinder piston rod, and the other end of the first wire rope is fixed at the tank top; one end of a second wire rope is connected with a second oil cylinder piston rod, and the other end of the second wire rope is fixed at the tank top. By the adoption of the adjusting device, relatively high-precision pretension of the wire ropes and automatic adjustment of the wire rope tensioning forces during the vault gas lifting process are realized, and the wire rope tensioning forces remain constant all along.