At　present,　monopile-supported　offshore　wind　turbines　(MOWTs)　are　widely　used　in　offshore　wind　farms.　The　influence　of　blade　flexibility　on　the　dynamic　behaviors　of　MOWTs　excited　by　waves　and　earthquakes　was　investigated　in　this　study.　Numerical　analysis　models　were　established　for　5　MW　and　10　MW　MOWTs,　incorporating　flexible　and　rigid　blade　configurations.　The　modes　and　natural　frequencies　of　the　full　system　were　compared　between　these　two　numerical　models,　and　their　dynamic　responses　were　evaluated　under　wave-only　and　earthquake-only　excitations.　It　was　revealed　that　the　influence　of　blade　flexibility　on　the　first-　and　second-order　modes　of　the　system　can　be　neglected.　The　dynamic　response　of　these　MOWTs　under　wave　excitation　can　be　predicted　by　the　rigid　blade　model,　where　the　maximum　relative　difference　is　less　than　5%.　However,　higher-order　modes　of　the　system　are　significantly　affected　by　the　blade　flexibility.　Under　high-frequency　excitations,　these　higher-order　modes　of　the　system　are　remarkably　stimulated.　Additionally,　a　large　relative　difference,　exceeding　50%,　is　detected　when　the　rigid　blade　model　is　used　to　predict　the　seismic　response　of　the　two　MOWTs.　Consequently,　the　blade　flexibility　should　be　adequately　modeled　when　predicting　the　dynamic　response　of　OWTs.