The invention discloses a fiber and silicon dioxide aerogel composite heat insulation material and a preparation method thereof. The fiber and silicon dioxide aerogel composite heat insulation material has thermal conductivity of 0.020 to 0.040W / m.K, porosity of 80 to 90 percent, density of 0.10 to 0.18g / cm<3>, a specific surface area of 800 to 1,000m<2> / g, a hydrophobic angle of 120 to 170 degrees and an aperture distribution of 2 to 50nm. According to the prepared heat insulation material, the thermal property of aerogel is maximally reserved, the mechanical performance of the aerogel is improved, the material has certain strength and toughness, the compressive strength of the material is 0.3 to 5MPa, and the bending strength is 0.5 to 1.5Mpa. A preparation process is simple, short in period, low in equipment cost and safe in production, and the prepared material has high heat insulation performance, has the advantages of low thermal conductivity, low density, environment friendliness, safety, nontoxicity, flame retardancy, anticorrosion and the like compared with an ordinary inorganic heat-preservation material, and can be applied to a heat insulation material for pipeline transportation, a firefighting material and the like.