The present invention provides a backplane and a backlight module and a liquid crystal display device using the backplane. The backplane includes: a bottom plate (2) and multiple side plates (4) connected to the bottom plate (2). The bottom plate (2) includes a base section (22) and a mounting section (24) connected to a lateral edge of the base section (22). The base section (22) has two ends that are each provided with a stepwise structure (222) for mounting a curved light guide plate to an inner side thereof. The mounting sections (24) has an outside surface that is curved for mounting a circuit board. The base section (22) has an outside surface on which first reinforcement ribs (226) and second reinforcement ribs (228) perpendicularly connected thereto are formed. The backplane and the backlight module and the liquid crystal display device using the backplane of the present invention help make the backplane simple in structure and easy to manufacture and simplifies the assembling operation and reduces the manufacturing cost.