The utility model discloses a slab burr removing device which comprises a supporting seat, a first baffle and a second baffle, wherein the first baffle and the second baffle are used for locating the two end portions of a slab. The first baffle and the second baffle are respectively connected with a lifting mechanism used for controlling the first baffle and the second baffle to move vertically. The lifting mechanism is connected to the supporting seat. A cutter roller I and a cutter roller II are arranged below the first baffle and the second baffle respectively. A supporting roller used for supporting and conveying the slab is arranged between the cutter roller I and the cutter roller II. The supporting roller, the cutter roller I and the cutter roller II are arranged on the supporting seat and make contact with the lower surface of the slab. The supporting roller, the cutter roller I and the cutter roller II are respectively connected with a motor. The slab burr removing device further comprises a controller and a detecting element arranged at the inner side of the cutter roller I and the inner side of the first baffle. The lifting mechanism, the motor and the detecting element are respectively connected with the controller. The slab burr removing device is high in slab burr removing rate and capable of effectively removing adhered slag of the lower surface after the slab is cut secondarily, reducing the quality objection caused by scars, and further improving the yield of steel boards.