When　a　single-pile　foundation　is　subjected　to　horizontal　loads,　the　vertical　friction　resulting　from　the　cross-sectional　rotation　of　the　pile　develops　into　an　additional　resistance　moment　from　the　soil　to　the　pile,　and　the　soil　at　the　pile　tip　also　forms　a　certain　additional　resistance　on　the　pile.　To　explore　the　influence　of　the　additional　resistance　of　the　pile　and　pile　tip　on　the　horizontal　bearing　features　of　the　single　pile,　deduces　the　discrete　numerical　solution　and　simplified　formula　solution　of　additional　moment　based　on　the　friction　model　of　sand　recommended　by　the　API　code　in　combination　with　the　ultimate　friction　enhancement　effect　caused　by　the　radial　soil　pressure.　Also　adopts　the　friction　model　of　clay　recommended　by　the　API　code　to　deduce　the　discrete　numerical　solution　and　simplified　formula　solution　of　the　additional　moment　in　the　cohesive　soil.　Based　on　the　hyperbolic　stress-displacement　model　and　the　separation　effect　of　pile-soil　interface,　deduces　the　discrete　numerical　solution　and　simplified　formula　solution　for　the　pile　tip　additional　moment　and　the　discrete　numerical　solution　of　pile　tip　horizontal　shear　force.　Furthermore,　proposes　a　finite　element　method　based　on　the　Winkler　foundation　beam　model　and　compiles　a　program.　By　comparing　with　the　experimental　data,　the　correctness　of　the　method　adopted　in　this　paper　is　verified.　The　parameters　of　the　horizontal　bearing　capacity　are　analyzed.　The　results　show　that,　as　the　ratio　of　pile　length　to　diameter　increases,　the　proportion　of　additional　resistance　in　the　total　horizontal　bearing　capacity　gradually　decreases,　while　the　proportion　of　additional　resistance　in　the　total　horizontal　bearing　capacity　shows　no　significant　changes　as　the　pile　diameter　increases.　Copyright　©2022　Engineering　Mechanics.　All　rights　reserved.