The invention discloses a preparation method of a hydrophobic type SiO2 nanometer aerogel heat-insulating material, and belongs to the technical field of preparation and forming of heat-insulating materials. The preparation method comprises the following seven steps of: carrying out heat treatment on a fibrofelt; preparing a SiO2 sol; soaking; gel aging; carrying out surface treatment; carrying out supercritical drying; and carrying out post processing. The SiO2 aerogel heat-insulating material prepared by utilizing the method disclosed by the invention has the advantages of nanometer level, good hydrophobicity and good comprehensive property.