The invention discloses a method for preparing silicon dioxide micropowder by using pulverized fuel ash extracted aluminum residue as a raw material and the silicon dioxide micropowder. The method for preparing the silicon dioxide micropowder by using the pulverized fuel ash extracted aluminum residue as the raw material comprises the following steps: step one. mixing sodium hydroxide and the pulverized fuel ash extracted aluminum residue, and calcining so as to obtain a calcination material; and step two. adding hydrochloric acid to the calcination material, reacting, filtering and drying so as to obtain the silicon dioxide micropowder. The method is characterized in that sodium silicate and sodium metaaluminate can be formed by mixing and calcining the sodium hydroxide and the pulverized fuel ash extracted aluminum residue; meanwhile, other carbon-containing substances in the pulverized fuel ash extracted aluminum residue can also be converted into carbon oxide so as to be removed; after the hydrochloric acid to the calcination material, aluminium chloride, sodium chloride soluble salt and silicon dioxide precipitates are generated by reaction, so that silicon dioxide is separated out; and the silicon dioxide micropowder with relatively high purity can be obtained by filtration and drying. The method is simple in technological operation, relatively short in operating period and suitable for large-scale recovery and production of large-scale silicon dioxide micropowder.