The　micrographs　and　optical　properties　of　Al-doped　ZnO　(AZO)　films　deposited　by　radio　frequency　(RF)　magnetron　sputtering　are　presented　in　this　paper.　The　AZO　films　termed　as　films　I,　II　and　III　were　sputtered　on　glass　substrates　heating　at　300　degrees　C,　400　degrees　C　and　500　degrees　C,　respectively.　The　micrographs,　crystal　structures　and　optical　properties　of　AZO　thin　films　were　analyzed　by　using　scanning　electronic　microscopy　(SEM)　images,　X-ray　diffraction　(XRD)　pattern,　optical　transmission　and　reflection　spectra　ranging　from　350　to　1000　nm.　As　the　substrate　temperature　increases　to　500　degrees　C,　the　film　III　exhibits　a　better　flatness　surface　and　a　larger　grain　size　of　similar　to　25nm　with　a　stronger　c-axis　orientation.　The　film　II　has　a　high　transmittance　of　greater　than　92%　in　the　visible　light　region.　We　also　show　that　the　films　II　and　III　have　significant　red-shift　band　gap　similar　to　3.00　and　similar　to　3.13eV,　respectively,　in　comparison　with　that　of　the　film　I　(3.31eV).　This　might　be　due　to　the　increasing　doped　Al　atoms　which　do　not　activate　due　to　segregation　at　the　grain　boundaries.