A last-stage pressure drop-adjustable multistage brush seal structure. The seal structure comprises a stator casing, gears, gear shafts, stator casing vent holes, a brush wire beam, downstream brush seal piece vent through holes, downstream brush seal upper side gear teeth, and the like. The stator casing is stationary. An upstream brush seal piece is fixedly mounted on the inner side of the stator casing. According to the last-stage pressure drop-adjustable multistage brush seal structure, reverse driving force moment in an inclined direction of brush wires is given to the gear shafts, torsion moment is transferred to the gears through the gear shafts, and the downstream brush seal piece gear teeth are engaged with the downstream brush seal piece and transfer the torsion moment to the downstream brush seal piece, such that the downstream brush seal piece rotates around a rotor.