An outdoor readable liquid crystal display device (200) includes a liquid crystal panel (210), a backlight device (220) and a light source control device. The backlight device (220) includes a plurality of red light emitting diodes (220r), green light emitting diodes (220g) and blue light emitting diodes (220b). The light source control device is used to adjust the backlight device (220) based on the light intensity of ambient light. When the light intensity of ambient light is lower than a predetermined light intensity of the liquid crystal display device (200), the red light emitting diodes (220r), the green light emitting diodes (220g) and the blue light emitting diodes (220b) of the backlight device (220) are sequentially energized to emit lights at a predetermined time lag. When the light intensity of ambient light is higher than the predetermined light intensity, the red light emitting diodes (220r), the green light emitting diodes (220g) and the blue light emitting diodes (220b) of the backlight device (220) are energized to emit lights at the same time.