Marshalling bed in big bar line is important rolling assistant equipment and plays an role in adjusting the production rhythm. The collocation and structural character of Marshalling bed in big bar line were described and its mechanics rhythm was analyzed in this paper. The clew items was introduced in marshalling bench design， in contrast of the structure. The paper can be a reference for more optimizing of marshalling bed in a big bar line. Frame structure can be varied， according to its own production process to choose suitable structure form.