The　AC　winding　losses　are　greatly　affected　by　the　design　of　air-gap　parameters　in　gapped　magnetic　components.　However,　there　are　no　effective　methods　to　test　their　AC　winding　losses　till　now.　After　introducing　the　mechanism　and　related　electromagnetic　theory　of　AC　winding　losses　of　gapped　magnetic　components,　a　novel　evaluation　and　test　method　for　AC　winding　losses　is　proposed,　which　is　based　on　the　equivalence　principle　of　MMF　of　a　winding　in　the　air-gap　to　replace　the　magnetic　voltage　drop　across　the　air-gap.　The　test　method　is　approved　to　be　effective　for　various　factors　which　influent　the　AC　winding　losses.　And　furthermore,　the　accuracy　is　also　approved　by　comparing　the　test　results　with　3-D　Finite　Element　Method　simulation　by　An　soft　Maxwell.　The　proposed　method　can　be　taken　as　a　simple　and　effective　measurement　method　for　gapped　magnetic　components　winding　losses　and　the　method　can　also　be　used　to　eliminate　the　winding　losses　from　the　total　losses　tested　by　some　methods　to　get　the　core　losses.　©　2015　Chin.　Soc.　for　Elec.　Eng..