Using the precipitation method, we propose a new process for the preparation of high specific surface area and large pore volume ZnO nanoparticles in unconfined space with Na4HCO3 and ZnSO4 center dot 7H(2)O as the reactants. The mixing performance of the reaction system was improved by gas atomization and continuous gas-based impinging streams before the precipitation reaction. By virtue of the gas environment and gas division, the obtained nanoparticles have a very good dispersion performance. Under optimal conditions, the ZnO nanoparticles were synthesized with a surface area of 88.89 m(2)/g, an average diameter of 7 nm, and a pore volume of 0.68 cm(3)/g. The influences of ZnSO4 concentration, pressure, and gas-liquid ratio on the properties of the synthesized nanoparticles were studied. This study aims to provide a feasible and economical way to produce better properties in nanosized ZnO particles, which are widely applied as a new, multifunctional material.