The structure of the drag chain: the shape of the drag chain is similar to the tank chain, which is composed of many unit chain links, and the chain links can rotate freely. The same series of drag chains are high inside, high outside, the same pitch, high inside the drag chain, and the bending radius R can be selected differently. The unit chain link consists of left and right chain plates and upper and lower cover plates. Each section of the drag chain can be opened, which is convenient to assemble and disassemble without threading. After opening the cover plate, cables, oil pipes and air pipes can be put into the drag chain. Separators may also be provided to separate the spaces within the chain as required.