ZnO microsturctures with flower-like and sphere-like morphologies have been successfully synthesized in ethylene glycol (EG) -water solution at 160 through a hydrothermal method. The volume ratio of EG to H2O plays an important role on the morphology control of ZnO. CH3COONH4 and NaOH were used as hydroxide source as well as complexing agents. The ZnO samples were characterized by XRD, FTIR and SEM. The optical properties of the final products were investigated by UV-vis absorption spectrometer and photoluminescence. The formation mechanism was also discussed.