A surface light source unit (2) includes a light source (21), a light guide plate (22), a reflective plate (23) and a diffusing plate (24). The light guide plate includes a light incidence surface (221) adjacent to the light source for receiving light beams, an emission surface (222) for emitting the light beams, a light reflection surface (223) opposite to the emission surface and a plurality of diffusion dots (224) formed on the light reflection surface. The diffusion dots contain a plurality of light scattering particles (225) having substantially global surfaces. The surface light source unit provides high uniform illumination for a liquid crystal display panel.