The　metro　running　intervals　with　more　and　more　existing　constructions　put　an　inevitable　influence　on　the　existing　construction　foundation.　In　order　to　control　the　impact　to　certain　limits,　it　is　necessary　to　adopt　effective　technical　measures　before　construction.　This　thesis　analyzes　the　effect　of　isolation　piles　in　controlling　building　deformation　during　the　tunnel　excavation　by　using　the　finite　difference　software　FLAC(3D),　which　takes　Beijing　subway　line　eight　as　an　example　and　the　construction　conditions　are　divided　into　no　reinforcement　measures　and　applied　isolated　piles.　By　the　contrast　analysis,　isolation　piles　can　effectively　control　the　building　deformation　through　stress　isolation　and　building　deformation　can　be　accord　with　requirement　of　standard,　then　to　ensure　the　safe　use　of　the　building.　In　addition,　this　thesis　can　give　references　for　the　same　kind　of　tunnelling　construction　in　the　future.　(C)　2011　Published　by　Elsevier　Ltd.　Selection　and/or　peer-review　under　responsibility　of　Society　for　Resources,　Environment　and　Engineering.