Based　on　the　prototype　tall　pier　bridge　on　Jingtai　Highway,　one　new　composite　tall　pier　is　designed.　By　utilizing　the　finite　element　software,　the　solid　models　are　established　for　the　nonlinear　stability　analysis　of　the　tall　pier　under　the　cantilever　stage,　and　the　beam　model　for　the　pier　after　construction.　Then,　the　stability　capacity　and　coefficients　were　obtained.　The　parametric　analysis　was　carried　out　to　investigate　the　influence　of　thickness,　of　the　yield　point　of　LYP　steel　plate,　of　the　height　of　specimens　and,　of　the　distance　of　a　tie　beam.　Numerical　calculations　show　that:　unbalanced　cantilever　construction　stage　is　the　most　unfavorable　condition　for　the　bridge,　and　the　failure　mode　is　compression-bending　in　longitude.　The　stability　coefficient　decreases　by　30%　compared　with　the　balanced　cantilever　construction.　Under　different　working　conditions,　the　maximum　strain　of　steel　tubes　occurred　around　0.1~0.2　height　of　the　CFST　column　on　the　compression　side.　With　the　increase　of　the　slenderness　ratio　of　the　pier,　the　stability　decreases　significantly,　and　the　failure　mode　gradually　transforms　from　elastoplastic　instability　to　elastic　instability.　The　increase　in　the　thickness　of　the　LYP　steel　plate　is　beneficial　to　the　improvement　of　the　stability.　It　is　favorable　for　the　stability　of　the　pier　that　the　distance　of　tie　beams　is　designed　according　to　the　experience　of　conventional　tall　piers,　i.e.　10　m~12　m.　Based　on　the　parametric　analysis,　proposed　are　a　new　simplified　model　for　new　composite　tall　piers　and　formulas　for　calculating　the　stability　capacity.　The　theoretical　calculation　results　are　in　a　good　agreement　with　the　numerical　results　when　the　slenderness　ratio　of　the　tall　pier　more　than　70.　When　the　slenderness　ratio　less　than　70,　it　is　accepted　to　calculate　the　stability　capacity　by　the　reduction　of　the　bearing　capacity　of　stocky　columns.　©　2025　Tsinghua　University.　All　rights　reserved.