In this study, yttrium was doped into ZnO gel and was spin-coated on the SiO2/Si substrate. Rapid thermal annealing of the as-prepared ZnO:Y thin films was performed at various temperatures.. The structural and photoluminescence characteristics were discussed. According to the results, the grain size of ZnO:Y thin films after various annealing temperatures is smaller than the ones without yttrium doping. Unlike ZnO thin films, the grains of ZnO:Y thin films are also separated instead of aggregating together since they were all annealed in the chamber atmosphere. The photoluminescence characteristic shows that only UV emission was obtained. However, the intensity of UV emission of ZnO:Y thin film was extremely stronger than ZnO thin film after the same annealing conditions. The intensity is also increased with increasing annealing temperatures. This phenomenon is considered to be caused by the quantum confinement effort for reducing grain size of ZnO:Y thin film.