Buckling-restrained　steel　plate　shear　walls　show　efficient　capacity　in　resisting　lateral　forces.　Conventionally,　these　systems　incorporate　concrete　elements　to　provide　buckling　restraint.　This　study　pioneers　the　integration　of　timber　as　buckling　restraint　components　to　form　a　steel-timber　composite　shear　wall.　Experimental　investigation　into　the　mechanical　performance　of　the　buckling-restrained　steel-timber　composite　shear　walls　was　conducted.　Subsequently,　numerical　simulation　was　carried　out　and　verified　with　the　test　data.　The　validated　finite　element　model　was　then　utilized　for　parametric　investigation,　seeking　a　comprehensive　understanding　of　the　performance　of　the　buckling-restrained　steel-timber　composite　shear　walls.　The　influence　of　key　design　parameters　on　the　performance　of　the　shear　wall　was　revealed.　The　design　parameters　include　the　layout　of　bolts,　the　height-to-　thickness　ratio　of　the　steel　plate,　the　thickness　of　the　buckling　restraint,　and　the　thickness　ratio　of　the　timber　and　steel　plate.　Design　suggestion　is　proposed　based　on　the　parametric　analysis.　Furthermore,　calculation　methods　for　the　ultimate　strength　and　initial　stiffness　were　proposed　and　validated　with　the　experimental　and　numerical　results.　The　formula　determining　the　minimum　required　thickness　of　the　timber　cover　plate　is　also　proposed　to　ensure　effective　out-of-plane　buckling　restraint.　The　studied　buckling-restrained　steel-timber　composite　shear　wall　exhibits　desirable　mechanical　properties,　providing　an　efficient　and　innovative　lateral　force-　resistant　system　for　multi-story　timber　structures.