Zinc oxide (ZnO) nanopolycrystalline films were successfully prepared by the modified successive ionic layer adsorption and reaction technique, which was based on the alternate immersion of substrate in the alkaline zinc precursor and deionized water. ZnO films were formed through an accumulation of ZnO crystal clusters. The size of the clusters ranged from 200 to 500 nm based on scanning electron micrographic images. Prepared ZnO films exhibited a wurtzite structure, with good microstructure, surface morphology, and optical properties. Ethanolamine was used as a complex reagent, which improved the adsorption of zinc complex with the substrate. Effects of processing parameters on the properties of ZnO nanopolycrystalline films were studied in detail. Intensive and sharp ultraviolet emission peaks at about 400 nm could be observed in the photoluminescence spectra.