Using chemical vapor deposition (CVD) method and purified air as carrier and diluent gas, ZnO thin films was prepared with zinc acetate on glass substrate. Crystalline and optical properties of ZnO thin films were respectively tested by X-ray diffractometer (XRD) and UV-light spectrophotometer. The results showed that crystal face (002) of thin films was preferred orientation. In the visible region, the transmittance was over 85%. When ZnO thin films was prepared at 500 °C, the crystallization of ZnO thin films was the best, and when the temperature was 450 °C, the grain size of thin films was the least, and internal stress was the least. With the substrate temperature increased, ZnO thin films both showed blue shift of the absorption edge and decrease of band gap.