In order to improve the light efficiency of wide color gamut liquid crystal displays (LCD), this paper proposed a reflective color filter. First, the enhancement effect of the light efficiency of the reflective color filter was calculated. Then, a multi-layer stack structure ([ABCCBA]⁸) of the color filter was designed based on low, medium, and high refractive index materials. Using white light emission diode backlight unit with yellow phosphor (YAG-LED) and quantum dot (QD) backlight unit, the light efficiency was increased from 17.4% to 32.9% and from 18.5% to 58.9%, respectively. At the same time, the color gamut of this structure also improved to 120.7% NTSC and 131.2% NTSC. Considering the role of the scattering film in the backlight module, the light efficiency of LCD with YAG-LED and QD backlight unit is still greater than 32% and 56% respectively when the incident light angle is within 20°. The color gamut remains essentially unchanged. These results hold significant potential for applications in wide color gamut LCD.