The invention discloses a method for preparing nanometer TeO2 from aerosol through microwave assistance. The method comprises the following steps of A, dispersing precursors into a polar solvent to form a colloidal solution or true solution, i.e., a precursor solution, wherein the mass ratio of the precursors to the polar solvent is (0.01 to 10):(90 to 99.9); B, atomizing the precursor solution prepared in the step A to form aerosol liquid drips; C, dripping the aerosol liquid prepared in the step B into a microwave generator to perform microwave radiation; then, performing drying roasting toform nanometer powder particles. The preparation method of the spherical powder has the advantages that the production period is short; the operation is simple and convenient; no pollution is caused;the microcosmic structures of the obtained spherical powder cannot be easily damaged; the amplification can be easily realized; the method is suitable for being popularized and applied. A product canbe widely used in the fields of corrosion resistance, bacterium resistance, electronic component materials, emission spectrum analysis and the like.