The invention discloses a laser cutting and dividing device. The device comprises a laser unit, a diffraction optical lens and a focusing mirror, wherein the laser unit is used for emitting a light beam; the laser beam separately forms focusing points on an upper surface, a lower surface and a middle part of a workpiece separately after passing through the diffraction optical lens and the focusing mirror; the focusing points are oval, and extend in the thickness direction of the workpiece; and oval extending length of the focusing point formed on the middle part of the workpiece is greater than that of the focusing points formed on the upper surface and the lower surface of the workpiece.