Abstract: The direct influence on urban rail transit FAO (fully automatic operation) line operation safety and efficiency is mainly from its core system. From the standing point of defining requirements, to formulate FAO core system investment plan scientifically and reasonably is the main issue faced by new line construction. Through comparative analysis of the estimates of Harbin Metro Line 2, Nanjing Metro Line 7, Nanning Metro Line 5, Fuzhou Metro Line 4, Xuzhou Rail Transit Line 6, and other GOA4 grade FAO core systems, the key technical factors influencing FAO core system investment is proposed considering requirements such as system and safety. It is discovered that the goal, positioning and operation requirements of FAO core system construction will directly affect the project investment amount. It is optimal to choose the FAO core system that is both meeting the operation requirements and the most basic, the most necessary, the most crucial.