Abstract: The present invention provides a back plate, backlight module and liquid crystal display device. The back plate is formed by splicing a plurality of splicing elements, wherein at least some of splicing elements are connected through rotation mechanism so that the back plate can switch between normal usage state and folded state, the back plate in folded state is smaller than in normal usage state, at least one of the splicing elements is an aluminum extrusion. Through using aluminum extrusion as a part of splice-type back plate and heat-dissipating device, the present invention improves heat-dissipation capability of backlight module and increases the life span of backlight module. In addition, because the splicing elements of back plate are connected in a rotatable manner, the back plate can be folded so as to improve the efficiency of storage and transport and reduce storage and transport cost.