Abstract: The super-pure barium titanate nano-powders were prepared by the microwave-liquid phase process,using titanium tetrachloride and barium chloride as raw materials and（NH₄）₂C₂O₄·H₂O as the precipitant and alcohol as dispersant.With the help of orthogonal experiment,the ebbect of reactive temperature and time for synthesizing precursor and deeomposition time under the microwave irradiating were studied By XRD、TEM tests,the particle size, crystal strncture and form were determined.The experimental results show that the tetragonal phase powders with the particle size less than 30nm are prepared within 50min by the microwave irradiating.With increase of microwave irradiating time,purity and crystallinity of the BaTiO₃ powders are improved,and their size is increased.