A two-step hydrothermal synthesis technique has been developed to obtained 1D ZnO nanostructures with adjustable aspect ratio and size distribution. The pre-curing process has important influence on the morphological, structural and optical properties. The LO phonons of the nanowires obtained by pre-curing for 24 h exhibit slight batho-shift in comparison with nanorods. The increase of the intensity ratio of ultraviolet to visible emissions in room-temperature photoluminescence spectra show the improvement in the quality of ZnO nanostructures as the pre-curing time prolonged. The fitting result of EX energy at T=0 is 3.382 and 3.370 eV for ZnO nanowires and nanorods, respectively.