To　establish　the　simplified　analysis　model　for　elastoplastic　seismic　response　of　reinforced　concrete　box　piers　subjected　to　bidirectional　seismic　excitation,　the　load-displacement　restoring　force　characteristics　subjected　to　the　bidirectional　cyclic　load　were　analyzed.　First,　the　basic　situation　and　the　failure　mode　of　the　biaxial　quasi-static　test　were　introduced.　Secondly,　the　calculation　methods　for　the　peak　displacement,　the　ultimate　displacement,　and　the　residual　deformation　of　the　box　pier　were　established　combined　moment　curvature　relationship　analysis　of　the　box　section　under　the　biaxial　compression　and　bending　load.　The　calculating　formulas　of　the　three-segment-line　load-displacement　skeleton　curve　and　the　unloading　stiffness　were　further　presented,　and　the　corresponding　theoretical　bidirectional　restoring　force　models　were　developed.　Finally,　the　theoretical　bidirectional　restoring　force　models　were　analyzed　and　verified　by　testing　results.　The　results　show　that　the　bending　failure　is　the　main　failure　mode　of　the　reinforced　concrete　box　pier　under　the　bidirectional　cyclic　load.　The　theoretical　load　displacement　skeleton　curve　and　the　hysteresis　curve　agree　well　with　the　test　ones,　and　the　theoretical　restoring　force　model　considering　the　bidirectional　cyclic　load　can　reveal　the　basic　anti-seismic　performance　of　reinforce　concrete　box　piers.　©　2016,　Editorial　Department　of　Journal　of　Southeast　University.　All　right　reserved.