The present disclosure discloses a backlight module and a liquid crystal display device, the backlight module includes a light source; a spectrally selective element arranged in the light path between the light source to the light-emitting surface of the backlight module, is used to pass through the red, green and blue spectral and limit or block the remaining spectrum. Through the above, the present disclosure may increase the color gamut of the display device and improve the color saturation of the display device.