Abstract: This paper begins with a description of the complexity of making up freight train marshalling plans. It is pointed out that an exact and rational result can be obtained by joint optimization of car flow routing and marshalling plan. Then, a mathematical model is built by transforming the problem of freight train marshalling plan into a calculation problem aboutmarshalling network graph, tominimize the total cost of car flows within the railway network. Finally, the algorithm of this model is approached.