Since there is no surface tension in the supercritical fluid, there is no additional pressure in the gel capillary pores at this point that is caused by surface tension. Therefore, the use of the gel under the condition of supercritical fluid is boring, the collapse of the gel structure caused by the additional pressure does not occur, the shrinkage of the gel during the boring process is avoided, and the gel network frame structure is adhered to Ultrafine aerogel with high specific surface area, uniform particle size distribution and large pore volume.