The ZnO nanorods and flower like structures were synthesized via two steps method; DC or RF sputtering to prepare the seed layer and hydrothermal method to growth the ZnO nanostructures. The seed layers were characterized by X-ray diffraction (XRD) and the morphology of ZnO nanostuctures were observed by scanning electron microscope (SEM). ZnO flower like structures were produced on seed layer prepared by RF or DC Sputtering of Zn target, and the ZnO nanorods were found on seed layer prepared by RF sputtering of ZnO target. The output current of ZnO nanorods was detected about 2-15 pA, the current increased with the increase of Zn(NO3)2.6 H2O solution concentration.