Abstract: A backlight module includes a first and a second light guide plate; a turning film; a first, a second, and a third light source module. The first light guide plate has a first light entrance surface, a first light-emitting surface, a first bottom surface, and a light guide structure formed on the first bottom surface. The second light guide plate is disposed above the first light-emitting surface and has a second light-emitting surface, a second bottom surface, a second light entrance surface, a third light entrance surface, and optical microstructures, wherein the second and the third light entrance surface are located on two opposite sides of the second light guide plate. The turning film is disposed between the two light guide plates. The first, the second, and the third light source module are disposed aside the first, the second, and the third light entrance surface, respectively.