High utilization efficiency of ambient light is needed for the design of the bright reflective LCDs. In transmissive made, the brightness can be easily controlled by a backlight. However, the light intensity of the reflective mode is limited within the ambient light. The loss of the incident light in the reflective mode results in darkening the LCD panel. It is an important point for the reflective display to increase the brightness as high as possible. In order to improve the efficiency, the property of a polarizer is discussed and the guideline is presented.