A chain is a component of a chain. A complete chain consists of many chain links connected to form a certain length of chain links, and then the chain links are connected to form the whole chain by connecting chain links or connecting shackles. In the chain design, at first, due to the load and speed of the silent chain requirements are not outstanding, so there is no too much attention to the problem of stress concentration and attenuation, the chain drive in the discontinuity is further obvious, in the pin hole cavity and chain joint body produced high stress. Furthermore, if the chain node line falls below the sprocket node line, the result is an up and down movement of the chain during engagement, which causes strong vibrations at high speeds. In recent years, the design of chain joints has been improved to increase the load and velocity capacity.