The present disclosure provides a liquid crystal display device, an image displaying method thereof, and a backlight control device by disposing the backlight control device between a backlight module and a liquid crystal display panel, wherein the backlight control device divides an image into a plurality of pixel units, calculates corresponding dimming coefficients of the pixel units, and adjusts a first optical signal output by the backlight module according to a plurality of dimming coefficients to output a plurality of second optical signals, thereby achieving local dimming and improving display contrast of the liquid crystal display device.