A backlight module includes an optical film set and a plurality of light source sets having a first light source and a second light source. The first light source generates a first chromaticity light while the second light source generates a second chromaticity light. The first chromaticity light mixes with the second chromaticity light in the space between the light source sets and the optical film set and then enters the optical film set. The first chromaticity light and the second chromaticity light have their own spectrum and both spectra fall into a first color region of the CIE 1931 color space. Within the first color region, the spectrum of the first chromaticity light is close to a second color region while the spectrum of the second chromaticity light is close to a third color region.