Spherical ZrO2 microparticles were prepared in a three-phase reactor by mixing two water-in-oil emulsions with normal heptane as oil phase and aqueous solutions of zirconium oxyacetate and ammonia as water phases, respectively. The principal factors that influenced the stability of emulsion were investigated, including the surfactant type, the volume of w/o, and the concentration of zirconium ion. In this work, four anion surfactants were tested, including Span 85, Arlacel 83, Span 80 and Span 40. The most stable reverse emulsions were obtained with the: surfactant Span 40. When w/o volume ratio was kept 1/100 using Span 40 or Span 80 as a surfactant, the ZrO2 microparticles with spherical morphology were successfully prepared in the reverse emulsions at various Zr4+ concentrations (from 0.5 M to 3 M). The particle sizes of ZrO2 are smaller for Span 40 as compared with Span 80 on the same Zr4+ concentrations. The crystalline phase of the ZrO2 powders after calcination at 750 degrees C for 2 h was tetragonal.