The　box-plate　steel　structure　is　a　box　structure　with　stiffened　steel　plates　directly　used　as　load-bearing　walls　and　floors.　In　order　to　improve　the　seismic　behavior　of　stiffened　steel　plate　wall　(SSPW)　of　box-plate　steel　structures,　grid　stiffening　plates　were　applied　on　SSPW　to　form　composite　stiffened　steel　plate　walls　(CSPWs).　Three　1/3　scale　specimens　were　tested　under　quasi-static　load.　The　effects　of　the　use　of　grid　stiffening　plates　and　the　constraint　of　relative　sliding　between　the　grid　stiffening　plate　and　infill　plate　on　the　failure　mode,　bearing　capacity　and　deformation　performance　were　studied.　The　finite　element　model　was　established.　The　effects　of　axial　compression　ratio,　height-to-thickness　ratio　on　the　bearing　capacity　of　CSPW　were　studied.　The　results　show　that　the　grid　stiffening　plate　can　restrict　the　buckling　of　CSPW　and　improve　the　stiffness,　bearing　capacity　and　energy　dissipation.　Moreover,　the　energy　dissipation　and　displacement　ductility　ratio　are　improved　by　42.4%　and　39.6%　due　to　the　relative　sliding　mechanism　of　the　grid　stiffening　plate　and　infill　plate.　The　simulation　shows　that　the　peak　load　decreases　with　the　increase　of　axial　compression　ratio　and　height-to-thickness　ratio.　When　the　axial　compression　ratio　is　not　more　than　0.6　and　the　height-to-thickness　ratio　is　between　300　and　500,　the　simulation　values　of　peak　load　of　all　CSPWs　are　larger　than　the　results　obtained　by　the　full-section　plastic　theory　according　to　JGJ　/T　380-2015.　For　the　bearing　capacity　and　out-of-plane　deformation,　it　is　recommended　that　the　limits　of　axial　compression　ratio　is　not　more　than　0.6　and　the　height-to-thickness　ratio　is　between　300　and　400.　©　2021,　Editorial　Office　of　Journal　of　Building　Structures.　All　right　reserved.