In　order　to　realize　the　fully　stressed　criterion,　that　is,　the　stress　of　the　nonlinear　engineering　structure　is　uniform　along　the　height　direction　under　the　action　of　wind　load　or　ground　motion,　the　section　size　of　the　continuous　structure　is　optimized　based　on　mechanical　analysis.　The　engineering　structure　is　simplified　as　a　continuous　cantilever　with　variable　cross-section,　and　its　material　constitution　is　nonlinear.　The　wind　load　and　ground　motion　are　represented　by　three　kinds　of　horizontal　static　loads:　uniform　load,　inverted　triangle　load,　and　inertia　force　related　load.　In　order　to　meet　the　needs　of　different　projects,　hollow　circular　section　and　box　section　are　designed,　respectively.　By　establishing　different　expressions　of　section　moment,　the　optimal　section　size　distribution　is　solved.　Then　the　optimal　stiffness　distribution　of　nonlinear　structure　is　proposed.　The　correctness　of　the　theory　is　verified　by　the　finite　element　method.　The　results　are　suitable　for　the　elastic　and　elastic-plastic　stages　of　the　structure,　and　are　effective　for　both　static　loads　and　dynamic　actions.　The　optimal　section　size　distribution　and　structural　shape　are　different　under　different　loads.　Finally,　a　practical　design　example　is　shown.