The　double　rectangular　tube　assembled　buckling-restrained　brace　is　a　new　type　of　buckling　energy　consumption　buckling-restrained　brace.　Because　of　its　external　restraining　members,　which　are　bound　by　high-strength　bolts,　its　mechanical　mechanism　is　more　complicated　and　its　failure　modes　are　more　varied.　In　this　study,　the　double　rectangular　tube　assembled　buckling-restrained　brace　composition　and　three　types　of　end　constructions　are　introduced　in　detail.　The　influences　of　different　design　parameters　on　the　performance　of　double　rectangular　tube　assembled　buckling-restrained　brace　are　studied　by　numerical　analysis　methods;　the　possible　failure　modes　and　the　influence　of　the　end　strengthening　construction　of　double　rectangular　tube　assembled　buckling-restrained　brace　are　also　investigated,　and　a　number　of　suggestions　are　proposed　to　improve　this　design.　This　study　shows　that　the　pinned　double　rectangular　tube　assembled　buckling-restrained　brace　has　four　types　of　typical　failure　modes,　namely,　overall　buckling　failure,　external　end　local　pressure-bearing　failure,　bending　failure　of　the　extended　strengthened　core　region　and　bolt　threading　failure.　Rational　design　can　prevent　a　buckling-restrained　brace　from　losing　its　load-bearing　capacity.　In　addition,　compared　with　the　end　strengthening　scheme　with　an　external　hoop,　the　end　strengthening　scheme　with　a　strengthened　bench　can　improve　the　load-bearing　capacity　of　the　double　rectangular　tube　assembled　buckling-restrained　brace　more　effectively,　and　a　reasonable　design　can　also　save　materials.