The invention discloses a method used for pressure variable accelerated solvent extraction rapid preparation of aerogel. The method comprises following steps: 1, a certain amount of an inorganic silicon source and water are mixed for dilution, a certain amount of an acid is added so as to obtain a salt-containing silicon sol, and a certain period of reaction is carried out so as to obtain a gel; 2, under periodic pressure changing conditions, an organic solvent aqueous solution with a concentration increasing with time is adopted for accelerated solvent extraction of the gel obtained in step 1; and 3, the processed gel obtained in step 2 is subjected to drying. The method is simple in operation process, short in production period, and low in energy consumption; the obtained aerogel is complete in structure, low in heat conduction coefficient, and high in mechanical strength.