The present invention discloses a backlight module including a solar collector, a number of fibers, a light bar, an optical mixing block and a light guide plate. Each of the fibers includes a light incident end and a light output end. The solar light collector traces the sun and collects the solar light. The light incident ends are connected to the solar light collector and transmits the collected solar light to the light output end. The light bar includes a number of point light sources. The point light sources and the light output ends of the fibers are set on the light bar. The solar light collected by the solar light collector enters the optical mixing block to mix via the light output ends of the fibers and emits into the light guide plate to be spread as an even surface light source.