A plate-to-plate connecting structure includes a first plate piece and a second plate piece. The first plate piece and the second plate piece have a first concave/convex connecting side and a second concave/convex connecting side connected with a corresponding concave/convex means; the first concave/convex connecting side has a first top edge and a second bottom edge, and the second concave/convex connecting side has a second top edge and a second bottom edge; the first top edge and the first bottom edge have top concave parts and bottom concave parts; the second top edge and the second bottom edge have top convex parts and bottom convex parts; the top convex parts are protruded into the corresponding top concave parts for forming a mutual blocking status; and the bottom convex parts are protruded into the corresponding bottom concave parts for forming the mutual blocking status.