The waterway is bore with vessels,whose OD points compose the traffic flow.The waterway transit capacity is the waterway bearing capacity of traffic.To study waterway transit capacity,we introduce the network model,regarding the ports as the nodes and the legs as the lines in the network mode.Considering the cargo flow OD structure,which is closely related to the channel transit capacity,we establish the network model with OD structure,in which the cargo flows between the arbitrary original point and destination port is the variables,the sum of all goods flows or freight turnovers is the objective function,subject to the leg transit capacity,port throughput capacity and obstructing transit capacity constraints.