This　research　relies　on　shield　interval　engineering　of　the　construction　using　the　mining　method　of　Beijing　Metro　Line　8　near　the　bottom　of　existing　subway　tunnel　line　10.　In-situ　test,　on-site　settlement　monitoring　and　numerical　simulation　are　used　to　analyze　the　construction　process　of　pipe　curtainused　in　the　construction　engineering　of　new　subway　tunnel　under　the　existing　subway　tunnel.　Under　the　protection　of　the　pipe　curtain　pre-support　system　in　the　engineering　the　influence　of　the　constructing　process　in　new　metro　double　line　tunnel　near　the　bottomof　existing　subway　tunnelon　the　perturbation　deformation　of　the　stratum　is　analyzed,furthermore　the　numerical　solutions　are　compared　with　the　field　monitoring　data.　The　conclusions　can　be　drawn　as　following:　under　the　action　of　the　curtain　support　system,　the　construction　perturbation　of　new　subway　tunnel　to　uppersurrounding　stratum　is　mainly　stem　from　the　settlement　of　the　upper　strata.　During　the　construction　of　the　metro　double　line　tunnel,　the　subsidence　caused　by　the　construction　of　the　left　and　right　tunnels　has　the　superposition　effect.　Under　the　action　of　the　pre-support　system,　the　existing　structuressettlement　deformation　derived　fromthe　constructing　of　new　tunnels　near　the　bottom　of　existing　subway　tunnel　can　be　controlled　within　the　allowable　range.　This　research　will　provide　important　reference　frames　to　improve　the　design　and　construction　of　the　relevant　underground　crossing　project.