I-rib　stiffened　plates　are　the　basic　components　of　steel　boxes,steel　arches,steel　toweres　and　steel　pieres　in　bridge　structures.The　stability　of　stiffened　plate　under　compression　is　the　focus　of　steel　bridge　design.To　study　the　overall　stability　performance　of　stiffened　plates,I-rib　stiffened　plate　specimens　with　different　geometric　dimensions　were　designed　for　an　axis　compression　test.　The　initial　geometric　imperfections　of　specimens　were　measured,　and　corresponding　finite　element　models　were　established.　The　effects　of　the　constitutive　relationship,residual　stress,and　initial　geometric　imperfections　were　considered.　The　stability　reduction　coefficients　were　obtained　by　massive　numerical　calculations　and　compared　with　national　codes.Analytical　results　show　that　the　imperfections　of　the　specimen　are　high　in　the　middle　and　low　on　both　sides　along　the　plate　width,and　have　randomness　in　the　initial　bending　direction.For　the　medium　and　long　column　specimen,bending　instability　deformation　occurs　in　the　middle　of　the　specimen,and　the　ultimate　bearing　capacity　of　the　stiffened　plate　side　bending　is　higher　than　that　of　the　stiffener　side.For　the　short　column　specimen,the　out-plane-buckling　deformation　occurs　in　the　middle　of　stiffened　plates　and　stiffeners　end.　With　the　increase　of　slenderness　ratio,the　instability　characteristic　of　axial　average　stress-displacement　curve　for　the　specimen　with　stiffened　panel　side　bending　is　more　obvious.The　stability　coefficients　of　test　and　finite　element　model　are　higher　than　the　class　B　column　curve　in　the　Chinese　steel　bridge　code.　Using　the　class　B　column　curve　in　the　Chinese　code　for　calculation　is　safe.　©　2023　Editorial　Board　of　Journal　of　Basic　Science　and.　All　rights　reserved.