The　increase　in　the　capacity　of　urban　buildings　has　led　to　higher　requirements　for　the　bearing　capacity　of　pile　foundations.　The　pile-soil　interaction　is　an　important　subject　in　studies　on　the　horizontal　bearing　capacities　of　pile　foundations,　which　are　of　significance　to　improve　the　design　theory　of　pile　foundations　and　guide　engineering　practices.　Based　on　the　Vesic　expansion　theory,　according　to　the　characteristics　of　the　soil　stress　after　the　horizontal　displacement　of　the　pile　body,　assumed　to　have　an　elliptical　nonuniform　distribution,　the　effects　of　the　vertical　stress　changes,　rotation　and　deflection　of　the　pile　foundation,　and　pile-soil　friction　on　the　lateral　soil　resistance　were　comprehensively　considered.　A　calculation　formula　for　the　soil　resistance　on　the　pile　side　under　horizontal　loads　is　derived.　A　method　of　p-y　curve　based　on　the　stress　increment　is　obtained.　A　mechanical　model　of　the　pile-soil　interaction　in　a　two-dimensional　plane　state　is　established.　The　applicability　of　the　method　is　verified　by　examples.　The　influences　of　pile　and　soil　parameters　are　analyzed　in　detail.　According　to　the　comparison　of　the　results　calculated　using　this　method　to　those　obtained　by　the　model　test,　the　theoretical　method　proposed　in　this　study　is　used　for　the　calculation　of　the　mechanical　response　of　the　soil　on　the　pile　side　under　horizontal　loads.　The　results　obtained　by　this　method　are　in　good　agreement　with　the　measured　data　in　the　model　test,　particularly　when　a　larger　horizontal　displacement　of　the　pile　foundation　is　produced.　Through　the　computation　and　analysis　of　the　pile　and　soil　parameters,　the　influences　of　the　pile　diameter,　internal　friction　angle,　and　deformation　modulus　of　the　soil　on　the　soil　stress　around　the　pile　are　analyzed.　In　addition,　the　change　rules　of　the　radial　and　tangential　stresses　of　the　soil　at　different　locations　around　the　pile　are　obtained.　©　2021,　Editorial　Department　of　China　Journal　of　Highway　and　Transport.　All　right　reserved.