The　performance　of　a　transcritical　refrigeration　cycle　with　an　alternative　refrigerant　CO2/DME　for　CO2is　theoretically　analyzed　and　calculated.　The　results　indicated　that　the　mixture　refrigerant　CO2/DME　is　filled　directly　without　changing　a　refrigeration　system　with　a　mass　fraction　of　DME　ranging　from　0%　to　10%.　In　the　similar　conditions,　the　CO2/DME　lowers　the　discharge　pressures　by　about　3　MPa,　and　the　coefficient　of　performance　(COP)　is　increased　by　about　4.3　percent.　The　influence　of　superheat　on　a　pure　refrigerant　CO2is　larger　than　that　of　the　mixture　refrigerant　CO2/DME.