The invention relates to a nanometer cellulose/polyvinyl alcohol gel composite material, which is characterized by comprising hydrogel and aerogel. A preparation method of the nanometer cellulose/polyvinyl alcohol gel composite material comprises the following process steps of 1, nanometer cellulose preparation by a chemical combination mechanical treatment method; 2, composite hydrogel preparation; and 3, composite aerogel preparation. The nanometer cellulose/polyvinyl alcohol gel composite material has the advantages that the composite aerogel belongs to a porous amorphous solid material consisting of nanometer level colloid particles or high-polymer molecules, and a unique open nanometer level porous structure and a continuous three-dimensional reticular structure are adopted, so the density is extremely low, the specific surface area is high, and the porosity is high, wherein the solid phase of the aerogel accounts for 0.2 percent to 20 percent of the total volume percentage, the characteristics of high adsorption catalytic capability, low thermal conductivity, low sound resistance, low refractive index and the like are shown, and wide application prospects are realized in the fields of aviation, spaceflight, chemical industry, metallurgy, energy-saving building and the like.