A backlight module including a light source, an optical wavelength conversion film, a first group of optical films, and a second group of optical films is provided. The light source is adapted to emit a first light. The optical wavelength conversion film is adapted to convert the first light into a second light with a different wavelength. The first group of optical films is disposed between the light source and the optical wavelength conversion film. The optical wavelength conversion film is disposed between the first group of optical films and the second group of optical films, wherein a ratio of a transmittance of the second group of optical films for the second light to a transmittance of the first group of optical films for the first light is larger than or equal to 45%. Thus, the backlight module has a uniform light-emitting color.