The present invention discloses a backplane, a backlight module, and an LCD device. A backplane comprises a heatsink plate and a supporting plate connected with the heatsink plate; the heat conductivity of the heatsink plate is larger than that of the supporting plate; the heatsink plate or the supporting plate is provided with reinforcing ribs in the joint. In the present invention, metal with good heat dispersion and common material with low cost are respectively adopted and joined according to different radiating areas of the backlight module; then, the heat dispersion is ensured and meanwhile, the cost is reduced. The reinforcing ribs are added in the joint so that the strength of the joint is enhanced and the backplane is tightened and durable.