This　paper　considers　a　reliability　model　for　multi-state　systems　(MSS)　with　common　bus　performance　sharing.　The　MSS　consists　of　heterogeneous　components　with　different　performance　and　demand　levels　and　a　common　bus　performance　redistribution　system.　Each　component　may　degrade　and　thus　have　different　performance　levels　to　satisfy　its　own　random　demand.　If　one　component　has　performance　that　exceeds　its　demand,　the　redundant　performance　can　be　redistributed　through　the　common　bus　with　limited　capacity　to　components　with　performance　deficiency.　The　entire　system　fails　if　there　are　components　with　deficit　performance　after　the　performance　sharing.　A　new　analytical　method　based　on　multi-valued　decision　diagrams　(MDD)　is　suggested　to　evaluate　the　reliability　of　the　considered　MSS.　The　MDD　method　encompasses　an　efficient　model　generation　algorithm　with　top-down　truncation　operation　rules　based　on　components＇　surplus　and　deficit　performance.　Furthermore,　case　studies　and　benchmark　research　are　presented　to　demonstrate　the　applicability　and　efficiency　of　the　proposed　approach,　as　compared　to　the　existing　method.