A backlight module which includes at least a U-shaped fluorescent tube, a first and a second heat-dissipating structure is provided. The U-shaped fluorescent tube includes a curved tube portion, two straight-tube luminous portions and two electrode portions. Of which, each of the two straight luminous sections has one end connected to one or the other end of the curved tube portion while the two electrode portions are correspondingly disposed at the other end of the two straight-tube luminous portions which are of equal length, parallel to each other and situated at the same side of the curved tube portion. The first heat-dissipating structure which envelops the entire or partial of curved tube portion is thermal-conductively connected to the curved tube portion. The second heat-dissipating structure which envelops one of the two electrode portions is thermal-conductively connected to the enveloped electrode portion.