A light guide plate includes an incident edge and a plurality of V-shaped grooves. The incident edge includes a tilted surface, a vertical surface, a top surface and a bottom surface. The top surface is configured in parallel with the bottom surface. The top surface joins with an end of the tilted surface. The bottom surface joins with the other end of the tilted surface. The plurality of V-shaped grooves extend in a predetermined direction and are configured on the tilted surface. When the light from a light source strikes on a tilted surface, on which V-shaped grooves make the light diffused, and the diffused light is in conformity on the incident edge, having no hot spot there.