Abstract: Al-doped ZnO films were prepared from Zn and AI alloy target by RF magnetron sputtering to study the effects of the oxygen on the properties of ZAO films.The relation between the transmittance and the O2/Ar ratio and the rule of optical properties under the same O2/At ratio were investigated.The results show that the best transmittance is obtained with a O2/Ax ratio of 1：35 at 200℃，while at 250"C the ratio of 1：30 is the best to get good quality films，at 300"C the ratio is 1：15. Under the same ratio of 1：25 the best transmittance is obtained at 200℃.

Key words: AI-doped ZnO films, O2/Ar ratio, RF magnetron sputtering, transmittance