In the water-in-oil (W/O) microemulsions based on anionic (AOT) surfactants, the ω value (molar ratio of water to surfactant), precursor, and surfactant could remarkably affect the synthesis of CuOZrO2 nanocomposite and the morphologies of the sol-gel products simultaneously. In this study, CuO-ZrO2 nanoparticles are synthesized using microreactors made of surfactant/water/n-hexane microemulsions and discusses the effect of different microemulsion variables on the particle size and particle size distribution by water-to-surfactant molar ratio. The obtained powders are characterized by DTA, XRD, SEM, EDS, and TEM and their physical properties are compared. For AOT surfactant the particle size increased with increasing the water to surfactant molar ratio. The particles size of CuO-ZrO2 nanocomposite in sample with anionic surfactant with molar ratio of 6 that calcined at 600˚C is between 15-20 nm.