A backlight module may include an optical substrate, at least one light guide pipe, and at least one first light source. At least one accommodation trench is disposed on the optical substrate for accommodating the light guide pipe. The first light source is disposed at one side of the light guide pipe and is arranged for emitting at least one first light into the light guide pipe. The first light is transferred in the light guide pipe and leaves the light guide pipe when being reflected by the optical substrate.