A　new　ejector　enhanced　auto-cascade　refrigeration　cycle　using　R134a/R23　refrigerant　mixture　is　proposed　in　this　paper.　In　the　new　cycle,　an　ejector　is　used　to　recover　part　of　the　work　that　would　otherwise　be　lost　in　the　throttling　processes.　The　performance　comparison　between　the　new　cycle　and　a　basic　auto-cascade　refrigeration　cycle　is　carried　out　based　on　the　first　and　second　laws　of　thermodynamics.　The　simulation　results　show　that　both　the　coefficient　of　performance　and　exergy　efficiency　of　the　new　cycle　can　be　improved　by　8.42-18.02%　compared　with　those　of　the　basic　cycle　at　the　same　operation　conditions　as　the　ejector　has　achieved　pressure　lift　ratios　of　1.12-1.23.　It　is　found　that　in　the　new　cycle,　the　highest　exergy　destruction　occurs　in　the　compressor　followed　by　the　condenser,　cascade　condenser,　expansion　valve,　ejector　and　evaporator.　The　effect　of　some　main　parameters　on　the　cycle　performance　is　further　investigated.　The　results　show　that　for　the　new　cycle,　the　achieved　performance　improvement　over　the　basic　cycle　is　also　dependent　on　the　mixture　composition　and　the　vapor　quality　at　the　condenser　outlet.　The　coefficient　of　performance　improvement　of　the　new　cycle　over　the　basic　cycle　degrades　with　increasing　vapor　quality.　In　addition,　there　exists　an　optimum　mixture　composition　to　obtain　the　maximum　coefficient　of　performance　for　the　new　cycle　when　other　operation　conditions　are　given.　The　optimum　mixture　composition　of　both　cycles　may　be　fixed　at　about　0.5　under　the　given　evaporating　temperature.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.