ZnO films are deposited on Al2O3 (0001) substrates in the temperature range from room temperature to 800 ℃ by using a pulsed laser deposition (PLD) technique. The influence of substrate temperature on the surface morphology, crystallinity and photoluminescence properties of ZnO films is analyzed by using X-ray diffraction, atomic force microscopy and photoluminescence spectroscopy respectively. The result given by the atomic force microscopy shows that the structure and crystallinity of the ZnO films are improved gradually when the substrate temperature is increased from room temperature to 400 ℃ and are reduced when the substrate temperature is increased up to 400 ℃. The ZnO films grown at the temperature of 400 ℃ have the best surface morphology and crystalline quality. The measurement result obtained by photoluminescence spectroscopy at room temperature shows that the ZnO films grown at the temperature of 400 ℃ have the highest ultraviolet emission intensity at its shortest emission wavelength of 386 nm.