An adjustment circuit for color sequential liquid crystal displays and an adjustment method thereof applied to a color sequential liquid crystal display are disclosed. The color sequential liquid crystal display receives a plurality of driving signals from a light-source driving circuit to generate a plurality of primary color backlights and at least one adjusted-color backlight and also receives one display driving signal. The adjusted-color backlight is generated behind one of three primary color backlights. By means of the adjusted-color backlight, the color and brightness of the frame are adjusted.