The invention discloses a backlight module and a back panel thereof. The back panel at least comprises a main back panel body, two bending structures, an optical diaphragm assembly and a glass layer, wherein the main back panel body is arranged on the bottom layer of the backlight module; the two bending structures are integrally molded and symmetrically arranged at two opposite sides of the mainback panel body; the optical diaphragm assembly is used for supporting the backlight module; and the glass layer is parallelly arranged on the optical diaphragm assembly. The invention is used for a split type liquid crystal backlight module, not only saves the use quantity of rubber frames, but also simplifies the structure of the backlight module, and also improves the steady degree.