A folding box includes a base, two side boards, and two end boards. The base includes a bottom plate, two side plates protruding up from opposite sides of the bottom plate, and two end plates protruding up from opposite ends of the bottom plate. Each side plate defines a number of first receiving slots. Each end plate defines a number of second receiving slots. A first shaft is mounted in each first receiving slot, and a second shaft is mounted in each second receiving slot. Each side board includes a number of first hooks protruding down from a bottom of the side board. Each end board includes a number of second hooks protruding down from a bottom of the end board.