Abstract:This paper presents an analysis of the complexity and influencing factors of the connection relations among the last trains in urban mass transit network and a model built to optimize the connection scheme of the last trains. And then, this paper presents a design of the graph notation and matrix notation of connection relations among different lines. Based on the matrix notation of connection relations and the consideration of the passenger flow demand and operational demand, an algorithm is derived to optimize the connection scheme of the last trains with a reference to the Kruskal algorithm of minimum spanning tree. A numerical example is given to illustrate the feasibility of the developed algorithm. This algorithm can be easily realized by computer program, which provides a decision support to the operational department of urban mass transit in compiling the connection plan of the last trains of the whole network.