In　this　paper,　the　nonlinear　dynamic　responses　and　analysis　of　the　monopile　for　offshore　wind　turbine　under　the　combined　loadings　of　the　horizontal　environmental　load　and　the　seismic　load　in　saturated　sand　site　were　carried　out　by　using　the　establishment　of　time-history　numerical　analysis　with　finite　difference　software.　Rationality　and　effectiveness　of　the　numerical　simulation　model　are　verified　by　comparing　with　the　centrifuge　test　data.　The　difference　of　dynamic　response　of　rigid　monopile　for　offshore　wind　turbine　under　conditions　of　seismic　loading　and　combined　loading　of　horizontal　environmental　loading　and　seismic　loading　was　analyzed　based　on　results　from　numerical　simulation.　It　was　further　discussed　the　influence　of　different　buried　depths　and　structural　masses　on　the　dynamic　response　of　monopile　under　combined　loading　conditions.　The　results　show　that　the　influence　of　horizontal-environmental　load　on　the　seismic　response　should　be　considered　in　the　design　of　offshore　wind　turbine　monopile　structure,　and　the　buried　depth　of　the　pile　should　be　considered　as　an　important　design　parameter,　while　the　impact　of　structural　quality　on　the　seismic　response　of　offshore　wind　turbine　monopile　structure　system　under　combined　loading　conditions　is　small.　©　2023　Science　Press.　All　rights　reserved.