This article reports the synthesis of ZnO nanostructures and its characterization by hydrothermalmethod. Different zinc salts such as zinc nitrate, zinc acetate and zinc sulfate are used as regents for the growth of ZnO nanostructures. The effect of counter ions (NO3 -, CH3COO- and SO4 2-) on the structural,morphological and optical properties is investigated. The different counter ions show the effect on the morphology of ZnO samples, in turn cause the different optical emission properties. Xray diffraction (XRD) patterns indicate that ZnO nanostructures possess the hexagonalwurtzite structure and ûne crystalline size, regardless of the counter ions. Scanning electronmicroscopy(SEM) and trans-premission electron microscopy (TEM) images show that various morphologies such as nanoflowers, nanoflakes and nanoprisms are obtained from zinc nitrate, zinc acetate and zinc sulfate precursors, respectively. The spectra of photoluminescence and Raman show ZnO nanostructures synthesized from various precursors have different intensity of emission bands, which shows the presence of various crystal defects and oxygen vacancies in the samples.