Abstract: Provided is a building block, comprising a building block body which is in a cubic structure and is composed of one first connecting surface provided with projecting portions and first recessed portions, and five second connecting surfaces. Also provided is a connecting structure of building blocks, in which projecting portions of one said building block are inserted into recessed portions of another said building block. Further provided is connecting structure of building blocks comprising a first building block and a second building block connected with the first building block; wherein a first building block body is composed of one third connecting surface and first recessed portions and five fourth connecting surfaces; a second building block body is composed of one fifth connecting surface and five sixth connecting surfaces. The present invention has advantages that different types of building blocks can be connected together and the connection forms are enriched.

Abstract: The present invention pertains to a connecting piece for toy track and a toy track. The toy track includes a supporting piece and the connecting piece for toy track. The connecting piece for toy track includes a flexible tube, a first connector, and a second connector. The first connector and the second connector are respectively connected to two ends of the flexible tube and coaxially arranged with respect to the flexible tube. The first connector is provided with a plug-in groove, and the second connector is provided with a plug-in convex part matched with the plug-in groove. The flexible tube has a first annular outer diameter, the first connector has a second annular outer diameter, and the second connector has a third annular outer diameter. The first annular outer diameter, the second annular outer diameter, and the third annular outer diameter are equal to each other.

Abstract: A building block and connecting structures thereof. A surface of the building block is a first connecting surface, and the rest of the surfaces of the building block are second connecting surfaces. The first connecting surface is provided with protrusions and grooves. The second connecting surface is provided with grooves. The protrusion can be connected to the grooves on the first connecting surface and the second connecting surface. Based on the above-mentioned structure and extensions thereof, the building block can be divided into at least six types with different structures. The building block and the connecting structures thereof have wide application range, are easy to popularize and use, provide great entertainment, and appeal to children.