To　ensure　better　horizontal　deformation　resistance,　the　pile　foundation　of　integral　abutment　jointless　bridges　(IAJBs)　should　be　designed　as　flexible　pile.　However,　the　calculation　algorithm　of　flexible　pile　in　relevant　codes　in　China　is　mainly　applied　to　the　laterally　loaded　pile,　and　whether　it　can　be　used　to　identify　the　flexible　pile　for　IAJBs　remains　a　tricky　issue　to　be　studied.　Therefore,　in　order　to　study　the　aseismic　performance　and　interaction　mechanism　of　the　single　pile-soil　system,　three　concrete　model　piles　with　different　lengths　were　tested　under　horizontal　low-cycle　reciprocating　displacement　based　on　a　specially　designed　pile　deformation　measurement　method.　The　result　shows　that　the　earliest　cracking　position　of　concrete　pile　is　between　3~6　times　of　pile　diameter.　The　deeper　the　pile　is　buried,　the　better　the　effect　of　pile-soil　interaction　with　a　deeper　location　of　the　deformation　characteristic　point.　Meanwhile,　stiffness　of　pile-soil　system,　horizontal　ultimate　bearing　capacity　and　aseismic　performance　is　improved　with　burial　depth　increased.　The　result　also　indicates　that,　when　the　pile-soil　system　reach　the　elastoplastic　stage,　the　flexible　performance　of　the　pile　will　gradually　degenerate　from　the　elastic　pile　to　the　rigid　pile.　Furthermore,　the　provisions　in　relevant　codes　in　China　are　not　safe　enough　when　evaluating　the　flexural　performance　of　the　pile　foundation　of　integral　abutment　jointless　bridges.　Hence,　it　is　recommended　to　use　the　Broms　method　for　the　benchmarking　calculation　in　practical　engineering.　©　2020,　Science　Press.　All　right　reserved.