The invention provides a rear display device casing and a display device. The rear display device casing comprises a casing; the casing is provided with an accommodating cavity for accommodating a loudspeaker; the accommodating cavity is provided with a sound outlet part for allowing the sound of the loudspeaker to go out. According to the scheme, the accommodating cavity capable of accommodating the loudspeaker is formed in the rear display device casing, and the loudspeaker is arranged in the accommodating cavity, so that the effects of preventing acoustic short circuit and improving the sound quality of the loudspeaker can be achieved; moreover, as the accommodating cavity is directly formed in the rear display device casing, only a die for the rear display device casing is needed to be modified while a loudspeaker box is not needed to be arranged independently, so that the cost is lower; besides, through the adoption of the scheme, the loudspeaker is mounted in the accommodating cavity of the rear display device casing, so that the assembly is simple.