Highly oriented ZnO nanorod arrays were suecessfully prepared on the indium tin oxide (ITO) substrate using a galvanostatic electrodeposition method.The ITO substrate was pretreated with ZnO nanoparticles via simple low-temperature solution route.The crystallinity,microstructure of surface,and optical properties of the obtained ZnO were characterized by X-ray diffraction,scanning electron microscope,and transmittance spectrum.The results indicate that the average diameter of ZnO nanorod arrays is about 30 nm,and the narrow size distribution ranges from 20 to 50 nm The nanorod arrays are growing along [001] direction with an orientation perpendicular to the substrate.When the wavelength of incident is over 380 nm,the ZnO nanorod arrays show a high optical transmission of above 95%.Furthermore,the possible growth mechanism of the nanorod arrays was discussed.