Abstract: Objective In light of the "Four-network Integration"（mainline railway, intercity railway, city railway and urban rail transit） development trend, the interoperation technology of CTCS-2（China train control system level 2） and CBTC（communication-based train control） is of great significance for promoting regional rail transit integration. Therefore, it is necessary to conduct in-depth research on dualsystem on-board technical solutions. Method An overall onboard system architecture is proposed based on the principle of "independent core safety devices, shared auxiliary equipment". The on-board ATP（automatic train protection） host devices for CTCS-2 and CBTC are set up independently to ensure safety, while ATO（automatic train operation）, DMI（driver-machine interface）, BTM（balise transmission module）, wireless communication units, and sensors are shared to enhance equipment reuse rate and reduce procurement cost. An innovative on-board ATP output switching unit is designed, employing two main control relays to effectively avoid time gaps in the switching process, and enabling seamless system transitions during train operation while ensuring the safety of ATP output commands. A detailed switching scheme for on-board equipment is developed, defining the switching procedures under different systems and the coordination mechanisms among various devices. A fullscale verification of the switching functionality is conducted in laboratory simulation environment. Result ＆ ConclusionThe designed on-board equipment architecture, output switching unit, and system switching scheme are rational and effective. During system switching, the train operation remains stable, and the speed curve is smooth and continuous, successfully achieving the design objectives and laying a solid technical foundation for subsequent engineering applications.