Abstract: To realize the organic combination of urban rail transit transportation capacity and efficiency, and to minimize the operation cost to the greatest extent under the condition of meeting the operation demands. Based on the characteristics of flexible train marshalling technology, the flexible marshalling technical schemes are introduced in detail, including the requirements of this technology for the signaling system, the selection of train coupling/uncoupling area, the setting of train coupling/uncoupling track section length, and the coupling/uncoupling scenarios. The key technologies of flexible train marshalling are introduced emphatically, such as the sending coupling train position report, the coupling train interface technology, the proximity parking technology, and the vehicle network fusion technology. Taking the application of flexible marshalling technology in Beijing Subway Line 3 as an example, its economy is analyzed, and the rationality and feasibility of this technology are proven.