Provided is a back plate component having reflective sheet reinforcing structure. The back plate component includes: a frame, a reflective sheet and a plurality of supporting film sheets. The frame includes a plurality of lateral beams and vertical beams, and at least one hollow part is included between the lateral beams and the vertical beams. The reflective sheet is attached to the frame, and includes a reflective surface and a back surface corresponding to the reflective surface. A portion of the back surface covers the whole hollow part. The plurality of supporting film sheets is attached to the back surface at a region corresponding to the hollow part, and includes a material the same as that of the reflective sheet. A liquid crystal display device is further disclosed herein.