The　2219　aluminum　alloy　was　used　more　and　more　widely　recently　due　to　the　excellent　properties.　The　gas　tungsten　arc　preheating　at　the　advancing　side　was　used　to　investigate　the　microstructure　and　the　properties　of　the　friction　stir　welded　joints.　The　results　show　that　the　mechanical　properties　of　the　friction　stir　welds　were　enhanced　with　arc　preheating.　The　tensile　strength　was　increased　by　12.3　%　with　the　difference　of　the　hardness　between　the　advancing　side　and　retreating　side　was　reduced　with　preheating　at　the　advancing　side.　It＇s　mainly　because　the　fluidity　of　the　material　at　the　advancing　side　was　improved　significantly　and　so　the　drastic　microstructure　transform　was　effectively　reduced　at　the　advancing　side.　Meanwhile,　the　distribution　of　grain　size　from　nugget　zone　to　the　advancing　side　was　more　gradual　with　the　extra　heat　added　to　the　hybrid　friction　stir　welds　than　that　in　conventional　friction　stir　welds.　Furthermore,　the　high　angle　grain　boundaries　at　the　transition　zone　of　preheated　friction　stir　welds　were　higher,　while　the　texture　strength　was　lower　than　that　of　conventional　friction　stir　welds,　indicating　that　the　dynamic　recrystallization　at　the　advancing　side　was　sufficient　with　preheating.