Currently,　the　conventional　design　method　for　ASHPs　is　only　to　ensure　that　the　required　output　heat　ing　capacity　at　specific　rated　conditions　can　be　provided,　without　considering　the　impacts　of　frosting　on　the　operating　performances　including　the　output　heating　capacity　of　ASHPs　when　operating　at　different　regions　with　different　climate　conditions.　Therefore,　in　this　paper,　a　novel　design　method　for　ASHPs　considering　both　the　required　output　heating　capacity　and　frosting　suppression　has　been　proposed,　and　its　development　is　reported.　A　prototype　ASHP　air　heater　for　use　in　the　cold　and　frosting　regions　in　China　was　designed　using　the　proposed　design　method,　and　tested　in　both　laboratory　and　field.　The　laboratory　test　results　showed　that　the　prototype　ASHP　air　heater　could　both　provide　the　required　output　heating　capacity　of　3　kW　at　its　rated　condition　of-12　degrees　C　DB　/　-13.5　degrees　C　WB,　and　achieve　the　desired　level　of　mild　frosting　at　the　standard　2　degrees　C　DB　/　1　degrees　C　WB　frosting　condition.　Furthermore,　the　field　results　indicated　that　the　prototype　ASHP　air　heater　could　maintain　a　better　operating　performance　due　to　better　frosting　suppression　than　a　conventional　ASHP　air　heater　with　the　same　rated　capacity　of　3　kW.　The　COP　values　of　the　prototype　ASHP　air　heater　were　21%　similar　to　37%　higher　than　those　of　the　conventional　ASHP　air　heater.　The　test　results　suggested　that　the　novel　design　method　could　be　used　to　help　design　ASHPs　that　can　not　only　provide　the　required　output　heating　capacity　at　rated　condition,　but　also　achieve　a　desired　level　of　frosting　when　operated　at　different　frosting　regions.　(C)　2020　Elsevier　B.V.　All　rights　reserved.