A packing box for packing tube lamps is provided. The packing box includes a middle case. The middle case is for packing two or more tube lamps. The middle case includes a support section and two bent sections at two opposite sides of the support section. The two bent sections are bent towards the support section. The support section and the two bent sections are substantially aligned in a width direction of the tube lamps before the bent sections are bent. The support section and each of the two bent sections respectively form one or more receiving cavities each of which is for receiving one of the tube lamps and are for wrapping the two or more tube lamps after the bent sections are bent. The tube lamps are easily packed by the packing box, and the tube lamps in the packing box are not easily damaged.