The invention discloses a cutting device on a paper diaper production line. The cutting device comprises a base, wherein second slide rails are arranged at the two ends of the upper surface of the base; second sliding blocks are arranged in the second slide rails; the second sliding blocks are connected with second linear motors; the second linear motors are electrically connected with a switch; a fixed part is fixedly arranged in the middle of the upper surface of the base; the top ends of the second sliding blocks are connected with bottom ends of supporting rods; first sliding blocks are connected through a connecting rod; mounting blocks are mounted at the lower ends of connecting pieces; cutters are mounted on the sides, away from the connecting pieces, of the mounting blocks; the top ends of the supporting rods are connected with the two ends of the lower surface of a supporting plate; first linear motors are mounted at the top ends, close to the supporting rods, inside the supporting plate; the first linear motors are electrically connected with the switch; and the first linear motors are connected with the first sliding blocks. According to the cutting device, the structure is simple, and the utilization is convenient.