The invention relates to a 
silicon dioxide 
aerogel material and a preparation method thereof. The method comprises the following steps: by using water glass as 
silicon source, adding an acid-containing 
organic solvent free of 
chlorine ions and 
fluorine ions to generate a precipitate of 
sodium ions, 
potassium ions and other 
metal salt ions, filtering to remove the precipitate to obtain high-purity silica 
sol, carrying out a 
sol-gel process, aging, acidifying, modifying, and 
drying to obtain the 
silicon dioxide 
aerogel material. The acidification before modification enhances the 
surface reaction activity of the silicon gel, thereby obviously enhancing the modification effect and efficiency. The method has the advantages of low cost and simple and efficient technique, is beneficial to 
mass high-efficiency production, is free of 
chlorine ions and 
fluorine ions in the whole technical process, and enhances the equipment 
operation safety and reliability; and the product can be used for heat preservation and 
thermal insulation of 
nuclear power and 
liquefied natural gas equipment and pipelines with higher requirement for 
corrosion resistance, and can also be used for 
thermal insulation in the field of 
aerospace, 
petrochemical engineering, track transportation, ships, automobiles, construction and the like.