The trans-reflective liquid crystal display device of this invention includes a plurality of data and gate lines defining a plurality of pixels, the pixels having a reflection region and a transmission region; a timing controller that receives, converts, and outputs image data; a switching unit that determines the output signal of the timing controller according to a transmission mode or reflection mode; a gate driver that receives a gate signal from the timing controller; a data driver that receives a data signal from the timing controller; a liquid crystal display panel with a TFT array substrate and a color filter substrate, the liquid crystal display panel displaying the image according to a gate pulse and a data voltage applied by the gate driver and the data driver; a sequential backlight including red, green, and blue lamps wherein, the backlight is turned on in a transmission mode to sequentially transmit the light into the transmission region and is turned off in a reflection mode.