Al　doped　zinc　oxide　(AZO)　thin　films　were　deposited　on　glass　substrates　with　radio　frequency　(RF)　magnetron　sputtering.　The　influence　of　substrate　temperature　(Ts)　and　RF　power　(Pw)　on　the　structural,　optical　and　electrical　properties　of　the　AZO　films　were　investigated.　The　X-ray　diffraction　patterns　show　that　AZO　films　deposited　over　100　degrees　C　have　hexagonal-wurtzite　phase　structures　with　highly　c-axis　preferred　orientations,　and　the　average　crystal　size　increases　upon　the　promotion　of　the　Ts.　When　the　Ts　increases　from　room　temperature　(RT)　to　250　degrees　C,　the　transmittance　and　the　optical　band　gap　of　the　AZO　films　increase　slightly,　whereas　the　resistivity　decreases.　The　sputtering　power　also　has　a　strong　effect　on　the　resistivity.　As　the　sputtering　power　increases　from　70　to　140W,　the　resistivity　firstly　decreases　to　the　minimum　at　the　power　of　110W,　and　then　it　increases.　It　is　also　found　that　annealing　is　an　effective　way　to　decrease　the　resistivity　of　the　AZO　thin　films　(Ts=250　degrees　C　and　Pw=110W)　from　similar　to　2x10-1　to　similar　to　3x10-3　Omega.cm.