In　practical　engineering,　the　pile　foundation　is　often　subjected　to　lateral　load　while　bearing　vertical　load.　And　the　lateral　and　vertical　bearing　capacity　of　pile　generally　are　calculated　separately　during　the　design　of　pile,　without　considering　the　effect　of　existing　vertical　load　on　the　lateral　capacity　of　pile.　Based　on　the　theory　of　elastic　foundation　beam,　the　stress　in　the　pile　units　of　laterally　loaded　pile　under　existing　vertical　load　are　analyzed,　the　pile-soil　friction　effect,　p-Δ　effect　and　the　effect　of　existing　vertical　load　on　soil　resistance　are　considered　comprehensively.　The　p-y　curve　formula　of　sand　considering　the　effect　of　existing　vertical　load　is　introduced,　and　the　theoretical　calculation　model　of　lateral　capacity　of　pile　under　existing　vertical　load　is　established.　The　corresponding　program　is　compiled　through　MATLAB　software.　The　mechanical　response　of　pile　is　obtained,　and　the　effects　of　different　existing　vertical　loads　on　the　lateral　capacity　of　pile　are　compared.　By　comparing　the　theoretical　calculation　result　with　the　experimental　result,　the　applicability　of　the　proposed　method　is　verified.　©　2020　Elsevier　Ltd