With　the　development　of　science　and　technology,　the　structure　of　engineering　system　has　become　increasingly　large　and　complex.　In　order　to　ensure　the　safety　and　stability　of　the　system　in　operation,　the　reliability　evaluation　of　complex　system　has　become　an　important　research　field.　However,　previous　studies　on　the　reliability　of　multi-state　systems　did　not　take　into　account　the　multi-level　performance　sharing　in　the　system,　and　it　has　been　unable　to　accurately　assess　the　reliability　of　such　complex　systems.　Therefore,　based　on　the　actual　engineering　system,　this　paper　proposes　a　multi-state　system　with　multi-level　performance　sharing　mechanism.　On　this　basis,　we　established　a　system　reliability　evaluation　model　using　universal　generating　function　technique.　Through　numerical　examples,　the　application　of　the　model　and　analyze　the　influence　of　different　parameters　on　system　reliability　are　demonstrated.　In　addition,　we　also　use　genetic　algorithm　to　optimize　the　allocation　of　components　in　the　system,　so　as　to　improve　the　reliability　of　the　system.　Different　from　the　previous　studies　on　system　reliability　with　common　bus　performance　sharing,　the　system　proposed　in　this　study　is　more　general.