ZnO thin fim has been synthesized by sol-gel spin coating method. The materials used were zinc acetate dehydrate as a basic material, isopropanol as a solution and diethanolamine as a stabilizer. The ZnO thin films were grown on FTO conductive glass substrate and post annealed at 500°C with annealed time consecutively 30, 60, 90, 120 and 150 minutes. The XRD results show that the crystal structure is wurtize hexagonal with size of 22 nm for 30 minute annealing time. The SEM results show a uniform homogeny round granules. UV-Vis measurements show a sharp transmission values and the decrease in their absorbance for all samples in the range of 310 to 430 nm wavelength. The band gaps are within 3.073 -3.140 eV.