W/O micro-emulsions were made of zinc nitrate aqueous solution with HMTA and kerosine in the presence of Span #80, and zinc oxide was precipitated in W/O micro-emulsions. The shape, size and particle size distribution of zinc oxide produced woe measured by SEM and Particle Size Analyzer. The effects of process parameter on the physical properties; of zinc oxide were experimentally examined. Spherical fine zinc oxide Particle with the average diameter of 0.1 - 1 ㎛ were obtained in W/O micro-emulsions, even if the initial zinc concentration of precipitating solutions and conversion were high.