We successfully synthesize four kinds of ZnO nano/microcrystals including dumbbell microrods, nanoflakes, nanoplates, and microrods by a simple wet chemical method. Growth duration is found to play a crucial role in the morphologies of these ZnO nano/microcrystallites. In addition, growth conditions are system-atically studied as a function of precursor concentration and temperature. The structural and optical characteristics of the ZnO samples are further investigated by X-ray diffraction, scanning electron microscopy, and photoluminescence spectroscopy.