The ZnO:Al（ZAO） films were deposited on glass substrates by using a DC reactive magnetron sputtering system. With the other parameters unchanged, the structural, electrical and optical properties of ZAO films were studied at the different annealing temperatures. The experimental results show that at the annealing temperature of 200 ℃ the ZAO thin film has better optical properties, the resistivity is 9.62×10-5 Ω·cm and the transmissivity in visible region is 89.2%.