A novel lifting system for a large-tonnage bridge erection machine comprises guide pulley components, a lifting crown block longitudinal girder, fixed pulley components, lifting crab traveling mechanisms, movable pulley components, lifting appliance components, lifting cart frames, lifting cart traveling mechanisms, a left platform, a right platform, left winches, right winches and longitudinal moving drive mechanisms. A single-lifting-appliance component and/or a dual-lifting-appliance component are/is connected with the bottoms of every two groups of the movable pulley components. By means of the lifting system, the overall structure is compact, simple and reliable, the overall weight is reduced greatly, the two-layer rope winding requirement of the winches can be met while the rope deflection angle requirement is met due to the novel threading mode, the steel wire rope service life is prolonged, stresses of all lifting rods on the lifting appliance components are uniform and consistent, the appearance size of supporting leg carrying roller boxes can be minimum on the premise that the use technological requirement is met, and the bridge erection machine fabrication cost is reduced.