The　p-y　method　as　a　simplified　analysis　tool　has　been　widely　used　to　analyze　the　behavior　of　laterally　loaded　piles.　This　paper　develops　a　novel　cyclic　p-y　elastoplastic　model　within　the　framework　of　the　single-surface　bounding　surface　theory.　The　model　can　capture　the　soil　stiffness　degradation　during　cyclic　loading　by　incorporating　the　cumulative　plastic　displacement　to　an　interpolation　function　of　the　elastoplastic　resistance　coefficient.　The　model　is　relatively　simple　with　only　four　parameters　that　can　be　determined　from　standard　soil　properties　and　stress-strain　responses　measured　in　direct　simple　shear　tests.　The　performance　of　developed　model　is　validated　by　predicting　the　cyclic　lateral　response　of　piles　installed　in　soft　clay　during　field　and　centrifuge　tests　published　in　the　literature.　The　model　can　reliably　simulate　monotonic　and　cyclic　responses　of　piles　under　different　lateral　loading　patterns,　and　capture　main　characteristics　of　the　pile-head　load-displacement　curve,　such　as　nonlinearity,　hysteresis,　displacement　accumulation,　and　stiffness　degradation.　It　can　also　predict　the　evolution　of　the　lateral　deflection　and　sectional　bending　moment　along　the　pile　during　cyclic　loading.