Cu-Al-O　thin　films　were　deposited　by　RF　magnetron　sputtering　using　polycrystalline　CuAlO2　target.　Fourier　transform　infrared　spectra　show　the　Cu-0,　Al-0　and　O-Cu-O　bonding　related　with　CuAlO2　phase.　Cu-Al-O　thin　films　show　good　transparency　in　the　visible　range,　and　the　transmittance　is　60%-70%　for　the　films　prepared　at　400　degrees　C　similar　to　500　degrees　C.　The　direct　and　indirect　band　gap　energies　estimated　are　3.52　eV　and　1.83　eV,　which　are　consistent　with　those　of　polycrystalline　CuAlO2　film.　In　the　range　of　close　room　temperature　(RT),　the　conductive　mechanism　of　Cu-Al-O　thin　films　belongs　to　the　thermally　activated　conduction.　The　electrical　conductivity　of　the　films　increases　and　then　decreases　as　the　substrate　temperature　increases.　The　film　deposited　at　500　degrees　C　has　the　higher　electrical　conductivity　(RT,　2.36x　10(-3)　S　center　dot　cm(-1)),　which　may　be　due　to　the　improvement　of　the　structure　of　Cu-Al-O　thin　film.