Abstract 2ZnO·3B2O3·3H2O is an industrially important zinc borate. Herein, 2ZnO·3B2O3·3H2O has been prepared via a rheological phase reaction method using zinc oxide and boric acid as starting materials. This route is facile and acceptable for green chemical synthesis, producing no pollution and giving a yield of near 100% of theoretical value. And in this method, the complete conversion of the starting materials can be achieved in the presence of only 0.04 mL water (one drop of water). The products have been characterized by X-ray powder diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA), scanning electron microscopy (SEM) and particle size distribution. The effects of experimental conditions on the products were investigated. The main factors that affect the formation of zinc borate are water volume, sealing state, reaction time and temperature.