中文摘要：

在对发车模式作了一定假设的前提下,通过对货物列车编发及运行的相关收益和损失的分析,给出了定点发车模式中最小编成辆数的理论计算公式;根据这个公式给出了最小编成辆数与列车在区段上的运行时间以及车流量大小之间的变化规律,并通过仿真的方法验证了理论分析的正确性.

英文摘要：

In the study of freight train departure mode,the research on the minimum number of cars in the fixed-point departure mode is a key issue.On the condition of some hypothesis of the freight train departure mode,by the analysis of car profits and locomotive loss in the course of car marshalling and train operation,the paper constructs a theoretical formula of determining the minimum number of cars in the fixed-point departure mode.And by this formula,the paper gives the change law of the minimum number of cars with the change of the time that the train runs in the railway sections and the change of the vehicle flow.And the change law is verified by the method of formulation.