Aluminium doped ZnO thin films(ZnO:Al) films were deposited on transparent TPT substrate at room temperature by RF magnetron sputtering. The effects of sputtering power on structural, optical and electrical properties were investigated by X-ray diffractometery (XRD), scanning electron microscope (SEM), UV-visible spectrophotometer, as well as Hall Effect Measurement System. Results revealed that the obtained film had a hexagonal structure and a highly (0 0 2) preferred orientation with the c-axis perpendicular to the substrate. The grain size and preferred orientation of crystallites showed dependence on the sputtering power. The optical transmittance of the ZAO films depended strongly on the sputtering power and decreased with increasing power.The transmittance of the ZAO film at 80W was over 80% in the visible region. And the electrical properties of the ZAO films are improved with the increase of the sputtering power.The resistivity of obtained film at 200W was 3.15×10-2Ω•cm.