Abstract: From the angle of metropolitan city railway opera-tion demand analysis, the currently existing CTCS-2 + ATO(Chinese train control system level 2 + automatic train operation) and CBTC(communication-based train control) signa-ling systems cannot fully meet the demands of public transport,networking, rapidity and automated operation of metropolitancity railways in China, and the function of their signaling sys.tems need improvement and expansion; based on urban railtransit interoperation CBTC system, scheme design of compati-ble signaling system is proposed and the overall requirementsand architecture of metropolitan city railway CBTC system arediscussed.