The present invention provides a laser cutting method, a display substrate and a display device. In the laser cutting method, the display substrate and the display device, as a cutting line is defined by two width defining dams on both sides of a region to be cut, the width of the cutting line can be adjusted by adjusting the distance between the two width defining dams. Thus, the width of the laser cutting line is controlled, and the effective use area of the substrate may be saved (and the material may be saved). Meanwhile, as the width defining dams are made of a laser reflective material, a laser beam irradiated onto the width defining dams is reflected without being absorbed by the width defining dams and thus transmitted to a corresponding region on the substrate. As a result, the generation of a carbonization region is avoided.