ZnNb2O6 ceramic powders was successfully synthesized by precipitation method with Nb2O5 and Zn(NO3)2·6H2O as raw materials and using aqueous ammonia as precipitating agent .The decomposition of precursors were investigated by differential thermal analysis(DTA).The phase contents were studied by the powder X ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy(TEM).The research showed that single phase ZnNb2O6 powders could be obtained at 800 ℃,the powder grain size decreased when the pH value increased. As pH=10,the average grain sizes with diameter of 100 nm could be obtained for ZnNb2O6 ceramics powders at 800 ℃.