A liquid crystal display device includes displaying each picture with two frame images in sequence; drive voltages of adjacent two sub-pixels on each frame image including a high drive voltage and a low drive voltage, and the drive voltages of each sub-pixel in the first frame image and in the second frame image including a high drive voltage and a low drive voltage; determining backlight brightness adjusting signals of each backlight sub-area according to the drive voltages of a first frame image area and a second frame image area corresponding to each backlight sub-area; the backlight brightness adjusting signals being in groups; and performing independent brightness adjustment on a backlight source of the sub-pixels of various colors in corresponding backlight sub-areas in respective frame images of a next picture according to the backlight brightness adjusting signal of each backlight sub-area.