A packing box can include a first cover, a second cover, a first sidewall, a second sidewall, a third sidewall, a fourth sidewall, and a bulkhead. The first cover and the second cover can be opposite to each other. The four sidewalls can be sequentially coupled end-to-end. The bulkhead can be received in the main box and be substantially parallel to the first cover and the second cover. Four edges of the bulkhead can be coupled to the four sidewalls, respectively. An inner receiving space of the main box can be divided into a first receiving cavity and a second receiving cavity by the bulkhead. A number of receiving portions can be defined on a surface of the packing box facing the first receiving cavity.