In　this　paper,　a　novel　Internally　Stiffened　Double　Steel　Plate　Shear　Wall　(ISD-SPSW)　is　proposed　based　on　the　concept　of　improving　the　buckling　mode　of　steel　plates　and　enhancing　the　lateral　resistance　of　steel　plate　shear　wall　(SPSW).　The　ISD-SPSW　consists　of　double　outer　steel　plates　on　both　sides,　inner　stiffened　rib　plates,　and　boundary　members.　The　seismic　behavior　of　ISD-SPSW　was　investigated　through　tests　and　numerical　simulations.　Five　ISD-SPSW　specimens　with　different　heights　of　the　wall,　thickness　of　the　outer　steel　plate　and　boundary　member,　and　different　numbers　of　internally　stiffened　steel　plates　were　investigated　in　cyclic　loading　tests.　The　performance　indexes　such　as　hysteresis　curves,　strain　curves,　and　skeleton　curves　of　ISD-SPSW　were　obtained.　The　finite　element　model　of　ISD-SPSW　was　established　and　verified　by　the　test　results.　The　test　results　reveal　two　distinct　failure　modes　for　the　ISD-SPSW.　The　first　mode　involves　the　failure　of　diagonal　tension　bands,　which　is　a　result　of　local　buckling　in　the　outer　steel　plates.　The　second　mode　is　characterized　by　the　overall　instability　of　the　shear　wall,　resulting　from　the　out-of-plane　deformation　of　the　boundary　members.　Lowering　the　height　of　the　wall　can　markedly　improve　the　load-bearing　capacity　and　out-of-plane　stability　of　ISD-SPSW.　Increasing　the　thickness　of　the　outer　steel　plate　can　improve　the　ultimate　load-bearing　capacity,　but　has　adverse　effect　on　the　boundary　members.　Reducing　the　thickness　of　the　boundary　member　can　significantly　reduce　the　load-bearing　capacity　and　seismic　performance.　Reducing　the　number　of　inner　stiffened　rib　plates　decreases　the　shear　load-bearing　capacity　and　energy　dissipation　capacity.　The　ductility　coefficient　of　most　specimens　is　greater　than　3.0,　indicating　that　the　ISDSPSW　has　good　ductility.　In　addition,　the　results　of　the　established　finite　element　model　are　in　good　agreement　with　the　test　results,　which　verifies　the　accuracy　of　the　model.