Taking the sequence of train breaking up and making up as the target of optimization,condidering the constrained source of shunting locomotives used for making up and breaking up operations,the mathematical model is established to find the breaking up and making up sequence of the largest-number departing on-time trains with the minimum total detention car hours.

The train classification sequence is usual to be arranged according to the departure time priority in the marshalling station.

Two efficient algorithms to choose the best possible user ordering for DPC are proposed.