In　this　paper,　a　CO2　supermarket　refrigeration　system　using　multi-ejector　and　dedicated　mechanical　subcooling　(MEJ　+　DMS)　is　proposed　to　solve　the　problem　of　low　performance　of　the　CO2　refrigeration　system　in　high　temperature　area　and　evaluate　the　feasibility　application　in　China.　A　detailed　thermodynamic　performance　analysis　is　conducted　with　MATLAB　software.　Furthermore,　the　annual　energy　consumption　and　seasonal　energy　efficiency　ratio　(SEER)　are　used　as　the　major　indicators　to　assess　the　system　performance　in　five　typical　representative　cities　of　diverse　climate　types　in　China.　The　results　indicate　that　compared　with　the　basic　booster　system　(BASE),　the　system　with　dedicated　mechanical　subcooling　(DMS),　and　that　with　multi-ejector　(MEJ),　the　MEJ　+　DMS　system　permits　not　only　reducing　the　operating　pressure　of　the　system　but　also　enhancing　the　maximum　COP　by　61.76%,　19.17%　and　20.21%,　respectively　at　the　ambient　temperature　of　40　°C.　Furthermore,　the　annual　analysis　shows　that　the　MEJ　+　DMS　system　can　save　energy　by　29.94%　and　increase　SEER　by　42.73%　in　hot　summer　and　warm　winter　zone.　The　new　proposed　system　has　the　advantages　of　greatly　promoting　system　performance　and　saving　energy　and　is　expected　to　replace　the　existing　CO2　supermarket　booster　refrigeration　systems.　©　2021　The　Authors