Nanostructured zinc oxide (ZnO) thin films were prepared through sol-gel method and spin-coating technique. ZnO thin films then were annealed at temperature of 350°C, 400°C, 450°C and 500°C. The thin films were characterized using field emission scanning electron microscope (FESEM), UV-VIS-NIR spectrophotometer and photoluminescence (PL) spectrofluorometer for morphology and optical properties study. The morphology study indicates that the particle size of ZnO increased with annealing temperatures. All thin films are optically transparent (~ 80 % in transmittance) in the visible light-NIR region. PL spectra reveal improved UV emission with annealing temperatures up to 500°C.