Evaluating　the　actual　heating　performance　of　Air　Source　Heat　Pump　units　(ASHPs)　is　essential　to　guide　the　development　and　operation　of　ASHPs.　The　Equivalent　Temperature　Drop　(ETD)　method　reported　in　previous　studies　provides　a　convenient　way　to　evaluate　the　joint　effect　of　ambient　temperature　and　relative　humidity.　However,　it　ignores　the　impact　of　the　configuration　and　operation　of　an　ASHP　on　its　frosting　performance.　To　enhance　the　applicability　of　the　ETD　method　to　different　ASHPs,　this　paper　introduced　the　Characteristic　Index　for　Configuration　and　Operation　(CICO)　to　improve　the　ETD　method.　A　Frosting　loss　correction　coefficient　(I　was　proposed　to　modify　the　ASHP　performance　prediction　model,　and　regression　relationships　between　(I　and　CICO　were　formulated　based　on　experiments　conducted　on　six　ASHPs　with　33　sets　of　different　CICO.　The　CICO-based　ETD　method　was　then　developed　and　validated　by　five　additional　ASHP　units.　The　results　show　that　the　CICObased　ETD　method　improved　the　accuracy　of　assessment　on　the　heating　performance　of　ASHPs　with　different　CICO　under　frosting　conditions,　with　a　reduction　in　relative　error　of　2-11　%　compared　to　the　previous　method.　This　study　provides　an　convenient　approach　to　give　more　precise　guidance　for　the　development　and　application　of　ASHPs.