The　tailings　microcrystalline　foamed　plate　(TMF　plate),　produced　from　industrial　waste　tailings,　has　limited　research　regarding　its　use　in　high-performance　building　walls.　Its　brittleness　under　stress　poses　challenges.　To　improve　its　mechanical　properties,　a　prefabricated　light　steel-tailings　microcrystalline　foamed　plate　composite　wall　(LS-TMF　composite　wall)　has　been　proposed.　This　LS-TMF　composite　wall　system　integrates　assembly,　sustainability,　insulation,　and　decorative　functions,　making　it　a　promising　market　option.　To　study　the　in-plane　performance　of　the　composite　wall,　compression　and　seismic　performance　tests　were　conducted.　The　findings　indicate　that　the　light　steel　keel,　steel　bar,　and　TMF　plate　in　the　composite　wall　demonstrated　good　working　performance.　Strengthening　the　TMF　plate　enhanced　the　restraint　on　the　light　steel　keel　and　improved　the　composite　wall＇s　compressive　performance.　Increasing　the　thickness　of　the　light　steel　keel　further　improved　the　compressive　stability.　Under　horizontal　cyclic　loading,　failure　occurred　at　the　light　steel　keel　embedding　location.　Increasing　the　strength　of　the　TMF　plate　was　beneficial　for　the　seismic　performance　of　the　composite　wall.　This　structural　configuration-incorporating　light　steel　keels,　TMF　plates,　and　fly　ash　blocks-enhanced　thermal　insulation　and　significantly　improved　in-plane　stress　performance.　However,　the　splicing　plate　structure　adversely　affected　the　seismic　performance　of　the　composite　wall.