Transportation system has evolved from relatively independent to integrated, which is a necessary path for constructing a modern and high-quality national comprehensive transportation network. Initially, this study conducts an in-depth analysis of the constituent elements and system characteristics of the multi-network integration of comprehensive transportation systems. Targeting the goal of establishing national strength in transportation and constructing a national comprehensive transportation system, the study subsequently provides a thorough review of the current research progress, development needs, and potential challenges of multi-network integration of comprehensive transportation systems. Finally, it proposes four primary tasks: Constructing a basic theory of multi-network integration with Chinese characteristics; building a national comprehensive transportation decision support platform; promoting the acceleration of the evolution of different transportation modes towards ‘multi-network integration’; and focusing on national and regional collaborative developments within major strategic scenarios. These initiatives support the construction of a convenient, smooth, economically efficient, green, intensive, advanced, safe, and reliable comprehensive transportation system.