The invention provides a backlight module which has no light guide plate and is even in brightness and a liquid crystal display device utilizing the backlight module. The backlight module comprises a back plate used for supporting, a reflection unit and a light scattering unit, wherein the reflection unit and the light scattering unit are arranged on the back plate in sequence. A concave cambered face concaving towards the back plate side is formed on one face, opposite to the reflection unit, of the back plate. The reflection unit is tightly attached to the concave cambered face, and a cavity is formed between the reflection unit and the light scattering unit. A luminous unit which provides incident rays for at least the reflection unit is arranged on the end face of the cavity.