A backplate molding device includes a top mold and a down mode. The top mold includes a plurality of punching heads having curved operation surfaces and a pressure plate. The punching heads are arranged in multi-sections and the pressure plate is arranged at a lateral side of the punching heads in the multi-section. An operation surface of the down mold is a curved surface engageable with the operation surfaces of the punching heads in the multi-section, and edges of the down mold cooperatively engages with the pressure plate to fix backplate materials. A punching process is applied toward the backplate material by bonding the operation surface of the punching heads with the operation surface of the down mold in sequence to plastically deform the backplate materials. The present disclosure also relates to a backplate molding method.