The invention provides a backlight module and a display device using the same. The backlight module comprises a light guide plate and a light source device; the light source device comprises an LED (Light-Emitting Diode) chip of which the light extraction surface is directly towards the lateral surface of the light guide plate. The display device using the backlight module, which is provided by the invention, comprises the backlight module. According to the light source device in the backlight module provided by the invention, due to the cancel of a lamp cavity, the size can be greatly reduced, so that the thickness of the backlight module can further be correspondingly reduced. Due to the cancel of the lamp cavity, a light emitting angle of the light source device can further be increased and light emitted by each surface of the LED chip can enter the light guide plate from the lateral surface, so that a light entrance angle of the light which enters the light guide plate is greatly increased, and thus, light entrance spots are avoided and brightness of the backlight module is further promoted. The display device using the backlight module, which is provided by the invention, adopts the backlight module provided by the invention, so that the overall thickness of the display device can be reduced, the cost can be further reduced and the display quality of the display device is greatly improved.