Air　source　heat　pumps　(ASHPs)　are　widely　recognized　as　energy-saving　and　environmentally　friendly　heating　and　air-conditioning　equipment　with　broad　applications.　However,　when　conventional　ASHPs　are　operated　at　a　low　ambient　temperature,　they　suffer　from　problems　such　as　high　discharge　temperature　and　low　heating　efficiency.　To　address　these　problems,　this　study　designed　a　new　type　of　dual　evaporator　combined　with　a　compressor　casing　thermal　storage　heat　pump　system　(DE-CCTS)　on　the　basis　of　a　low-temperature　air　source　heat　pump　water　heater　with　enhanced　vapor　injection　(EVI).　The　proposed　DE-CCTS　used　thermal　storage　phase　change　material　(PCM),　which　was　filled　in　the　secondary　evaporator　(the　thermal　storage　heat　exchanger),　to　recover　the　waste　heat　of　the　compressor　casing.　Unlike　that　in　the　original　system　under　different　ambient　temperatures,　the　suction　temperature　increased　by　0.1-1　degrees　C,　the　discharge　temperature　decreased　by　0.1-0.5　degrees　C,　and　the　coefficient　of　performance　(COP)　of　DE-CCTS　increased　by　0.85-4.72%　under　the　proposed　system.　These　effects　were　especially　evident　at　low　temperatures.