A packing box is disclosed. The packing box includes a box body having an inward concave forming four blocking portions at four sides, and a plurality of supporting members. The supporting member includes a big head end and a small head end fixedly connecting to the blocking portions. The small head end is arranged above an up surface of the blocking portion. A bottom surface of the big head end comprises an inward concave, the small head end of the supporting member of the packing box located at a lower altitude engages with the big head end of the supporting member of the packing box located at a higher altitude when the packing boxes are stacked.