通过研究城市轨道交通网络末班车乘客的换乘衔接问题，对城市轨道交通网络末班车的衔接关系的复杂性进行了分析，建立了以换乘人数最大化为目标的城市轨道交通末班车衔接方案优化模型，该模型的实质是求解加权有向图的最大有向无环子图；然后，设计合适的编码方式，采用类OX法进行交叉操作，提出了对城市轨道交通末班车衔接方案优化模型适用的遗传算法；最后，利用算例对提出的遗传算法进行了验证。结果表明：该算法能够快速求得较为优化的末班车衔接方案，易于计算机实现，可作为末班车计划编制的辅助手段，为城市轨道交通网络中各线路末班车时刻表的编制提供一定的决策依据。

Focusing on the transfer connection problem of last trains of urban mass transit network，this paper analyzed the complexity of the connection relationship of last trains of urban mass transit network and established an optimization model for the connection scheme of last trains of urban mass transit aiming at maximizing the number of passengers.The essence of the model is to solve the maximum directed acyclic subgraph of the weighted directed graph.And then，an appropriate coding method was designed，the ox like method was used for cross operation，and a genetic algorithm suitable for the optimization model of last trains connection scheme of urban mass transit was proposed.Finally，the proposed genetic algorithm was verified with an example.The result shows that the algorithm can quickly obtain a more optimized last trains connection scheme，which is easy to be realized by computer.This method can be used as an auxiliary means for the preparation of last trains schedule，and provides a certain decision-making basis for the preparation of last trains schedule of each line in the urban mass transit network.