The invention provides a paperboard cutting device for a corrugated carton. The paperboard cutting device comprises a workbench, two side frames, a mounting plate, a cutting plate, a cutting mechanism, a first driving mechanism, a second driving mechanism, a third driving mechanism and a fourth driving mechanism. A first conveying roller set is arranged between the cutting plate and the feed end of the workbench. A second conveying roller set is arranged between the cutting plate and the discharge end of the workbench. A cutting groove is formed in the cutting plate in the direction perpendicular to the conveying direction of the first conveying roller set. The cutting mechanism comprises a mounting base, a mounting column and a cutting knife used for cutting paperboards. The first driving mechanism is used for driving the first conveying roller set to rotate. The second driving mechanism is used for driving the second conveying roller set to rotate. The third driving mechanism is used for driving the mounting column to move in the extending direction of the cutting groove. The fourth driving mechanism is used for driving the cutting knife to move in the vertical direction. The paperboards are continuously cut through mutual cooperation of the first conveying roller set, the second conveying roller set, the cutting plate and the cutting mechanism.