The　Nb-doped　-Ga2O3　(-Ga2O3:Nb)　thin　films　have　been　deposited　on　the　Si　and　quartz　substrates　by　radio-frequency　magnetron　technique　in　argon　ambient.　The　effects　of　annealing　atmosphere　on　the　structural　and　optical　properties　of　-Ga2O3:Nb　thin　films　have　been　investigated.　The　crystallinity　of　-Ga2O3:Nb　film　is　improved　obviously　after　annealing.　An　increase　in　surface　roughness　is　observed　on　annealed　films.　The　bandgap　from　5.19　to　5.26　eV　is　obtained　after　annealing　in　different　atmosphere,　which　is　larger　than　the　5.09　eV　before　annealing.　Moreover,　the　red-shift　of　photoluminescence　emission　peak　is　observed　after　annealing,　and　the　annealing　atmosphere　has　an　influence　on　the　peak　intensity.