Abstract: Objective In the context of the ongoing integration of urban agglomerations and metropolitan areas in China, it is necessary to conduct in-depth research to support the integrated development of urban rail transit and city rail transit. Method Drawing on typical practices of multi-level rail transit integration in China and abroad, the main modes of integration between urban rail transit and city rail transit in China are sorted out, focusing on the implementation mechanisms of coordinated interchanges and throughoperation. The integration strategies are further explored, related to optimizing interchange layout, achieving fare integration, and adapting key technologies（e.g. power supply systems, rolling stock platforms, signaling systems, and dispatching and command systems）. Result ＆ Conclusion Preliminary progress has been made in integrating urban rail transit and city rail transit in China. However, bottlenecks remain in areas such as system interface standards, operational coordination mechanisms, and fare clearing systems. In future integration efforts, the institutional coordination and standard alignment should be strengthened, to promote a tiered technological implementation, and establish a unified rail transit system centered on a networked operational mechanism. This will effectively support the spatial optimization of metropolitan areas and urban agglomerations, as well as the improvement of commuting efficiency.