A backlight module includes a light guide plate and a lighting source. The light guide plate has a main body with a light incidence surface and a light emitting surface. A plurality of accommodating grooves are provided on the light incidence surface, and a plurality of light-separation grooves which are perpendicular to the accommodating grooves are provided on the light emitting surface. The light source includes a circuit board and a plurality rows of light bars welded on the circuit board, where each light bar is composed of a plurality of light emitting diode. When the light source is assembled to the main body, the circuit board is attached to the light incidence surface such that the light bars are disposed for the corresponding accommodating grooves. Therefore, the light-separation grooves can effectively optically separate the light when the light bars are illuminated.