A back plate of a curved display device of the present invention includes a first plate, a second plate, and a plurality of spacer units. The first plate has a first periphery, and the second plate has a second periphery. The second periphery is disposed on the first plate, forming an interlayer space therebetween. The first periphery is fastened to the second periphery. The first plate and the second plate are curved corresponding to each other. The spacer units are distributed in the interlayer space and are connected to the first plate and the second plate.