A light guide plate (10) includes a transparent plate (20), and a plurality of diffusing protrusions (30). The transparent plate includes an emitting surface (21), and a bottom surface (23) opposite to the emitting surface. The diffusing protrusions are distributed evenly on the emitting surface of the transparent plate, and are integrated with the transparent plate. The diffusing protrusions are hemispherical or sub-hemispherical, and a diameter of each diffusing protrusion is in the range from 10 m50 m. The light guide plate provides high emitting brightness and uniformity. The diffusing protrusions can diffuse light beams emitting from the emitting surface of the transparent plate, in order to achieve a plane light source having even brightness. The present Invention also discloses a method for fabricating the light guide plate.