The utility model discloses a laser back of body light source device and liquid crystal disply device, a serial communication port, include: laser lamp -house and light guide plate, laser lamp -house includes red laser, green laser and blue laser for produce the line source, the light guide plate includes side, plane of reflection and play plain noodles for convert the line source into area source, red laser, green laser and blue laser are arranged in the side of light guide plate order lamp strip formula, jet into the line source in the light guide plate, the warp the plane of reflection diffuse reflection forms the area source, by it jets out to go out the plain noodles. In this way, the utility model discloses realize that present laser display device is ultra -thin, produced image colour gamut scope is wider, characteristics such as the picture vividness has obtained improving by a wide margin, the excitation high, luminance is high, environmental protection, assembly are simple.