Packaging box and cardboard structure

A cardboard structure, comprising:

• a first surface and a second surface that is opposite to the first surface;
• a first sub-board is configured to bend to form a first box body, comprising a first plate area and a plurality of sidewall areas, wherein the first plate area along a first reference direction and a second reference direction are respectively connected to the plurality of the sidewall areas, the first plate area comprises a first opening, the plurality of sidewall areas are bent at least toward the first surface relative to the first plate area to form a first plate body and sidewall parts, and the first reference direction and the second reference direction are perpendicular;
• and
• a second sub-board is configured to bend to form a second box body, comprising a first accommodating area and a second accommodating area mutually connected, wherein the first accommodating area is bent to form a first receiving part, and the second accommodating area is bent to form a second receiving part,
• wherein in a first state, the second box body is located inside the first box body and blocks the first opening;
• and wherein in a second state, the first receiving part and the second receiving part are respectively connected to outside of the first plate body, and the first box body exposes an inner portion through the first opening.