ZnO thin films, as novel materials for Ⅱ-Ⅵ semiconductors, have excellent microstructural, optical and electronic properties. Ultraviolet (UV) stimulated emission is an outstanding merit of ZnO thin films. Nanostructured ZnO films with grain size of 28～35 nm have been prepared on quartz glass substrates by pulse laser ablation of Zn target in oxygen atmosphere. The structural and optical properties of the films were studied. ZnO thin films with typical c-axis (002) orientation were successfully deposited at a range of 100～250 ℃. The results obtained by X-ray diffraction (XRD) and photoluminescence (PL) measurements show that the strong UV emission centering is about 378～385 nm and deep-level emission centering about 518～558 nm in the room temperature PL spectra of the ZnO films. It is noteworthy that only strong UV emission (without deep-level emission) was obtained from ZnO film deposited at the substrate temperature of 200 ℃. This was attributed to its best crystallization.