Abstract: Objective City railways adopt CTCS（China train control system）, while urban rail transit employs CBTC（communication-based train control） system. Significant differences in technical architecture and functional logic between the two systems result in distinct content, methods, and focal points for their joint commissioning and testing. Therefore, it is necessary to carry out a corresponding comparative analysis for this issue. Method The technical differences between city railway CTCS-2+ATO system and urban rail transit CBTC system in joint commissioning and testing process are analyzed, with a focus on comparing and examining their approaches in functional verification, system interface debugging, and testing methods. Result ＆ Conclusion Technical references are provided in the research for the joint commissioning and testing work of CTCS-2 + ATO and CBTC systems. They can also serve as a key basis for breaking down technical barriers, promoting interdisciplinary integration and innovation of rail transit signaling systems, and achieving integrated operation of rail transit networks.