The Al-doped ZnO (AZO) films were deposited on the glass substrates by RF magnetron sputtering at different substrate temperatures. The effect of substrate temperature on the structural, optical, and electrical properties of AZO films was investigated. The results indicate each of the films has a preferential c-axis orientation. The grain size increases with substrate temperature increasing. All the films exhibit a high transmittance in visible region and have sharp ultraviolet absorption characteristics. The resistivity decreases with substrate temperature increasing up to 250oC, then increases for higher temperature.