Using　first-principles　evolutionary　methodology　for　structure　predictions,　we　investigated　the　structures　properties　of　AlxGa1-xN　alloys　with　different　Al　concentration.　Seven　unreported　and　low-energy　order　structures　have　been　found　successfully　by　enthalpy　calculations.　Especially　for　the　structure　of　Al0.5Ga0.5N　alloy,　the　eligible　distribution　of　Ga　and　Al　atoms　makes　the　structure　more　stable　than　regular　order,　suggested　previously　due　to　less　net　strain.　The　relative　distribution　mechanism　of　Ga　and　Al　atom　has　also　been　discussed.　All　predicted　structure　parameters　agree　well　with　recent　experimental　results　[ACS　Nano　2011,　5,　1291].　The　low　formation　enthalpies　and　spinodal　decomposition　temperature　have　been　studied,　which　indicate　high　self-adapting　stability　of　these　predicted　AlxGa1-xN　alloys　above　95K.　In　addition,　the　continuous　bandgaps　and　similar　absorption　spectrums　of　these　AlxGa1-xN　alloys　show　that　the　optoelectronic　properties　can　be　easily　tuned　by　varying　the　Al　concentration　in　AlxGa1-xN.