A backlight module includes a light guide plate and a flexible, looped strip. The light guide plate includes a light emitting surface for emitting light outwardly therefrom. The strip loop includes a brightness enhancement portion and a light-pervious base portion connected end to end. The strip loop is rotatable relative to the light guide plate such that the brightness enhancement portion and the light-pervious base portion can be selectively aligned with and face towards the light emitting surface. The light guide plate is positioned between the brightness enhancement portion and the light-pervious base portion.