The present invention provides a backlight module and a liquid crystal display device using the backlight module. The backlight module includes a light collector, a plurality of first optical fibers connected to the light collector, a plurality of first optical fiber splitters connected to the first optical fibers, a plurality of second optic fibers connected to the first optical fiber splitters, and a light guide plate arranged at one side of the second optic fibers. Each of the first optical fiber splitters includes a first light inlet and a plurality of first light outlets. The first light inlets are respectively connected to the first optical fibers and the first light outlets are respectively connected to the second optic fibers. The backlight module uses optic fiber splitters to split received sun light for making dense and uniform distribution of sun light at a light incidence site of a light guide plate.