The present invention discloses a display device and a backlight module. The backlight module comprises a waveguide, a reflector, a backframe and a shimming device. The reflector arranged behind the waveguide. The backframe carries and supports the waveguide and the reflector. An light inlet edge of the waveguide and the backframe is defined with a gap in which a shimming device is seated within the gap so as to effectively support the waveguide. This arrangement can effectively prevent the warpage or bending of the waveguide in the area of the light inlet area. Stabilizing the efficiency of illumination of the backlight module. As a result, the insufficient of illumination of the waveguide encountered by the prior art is avoided.