The invention discloses a nano-glass heat insulation paint and a preparation method thereof, belonging to the field of paint. The paint comprises component A and component B, wherein the polyalcohol component A is formed by mixing waterborne polyurethane and nano antimony tin oxide slurry according to the mass ratio of 4: 1-1: 1; curing agent is isocyanate curing agent; the mass ratio between thecomponent A and the component B is 10: 1; in the polyalcohol component A, the nano antimony tin oxide slurry is prepared by taking mixture of nano antimony tin oxide, water and absolute ethyl alcohol(mixing according to the volume ratio of 1: 1), and polymer anion dispersing agent as raw materials, and has the solid content of 20%; and the nano-glass heat insulation paint is prepared by taking the waterborne polyurethane, the nano antimony tin oxide slurry, the water, adhesive force accelerating agent, wetting agent, flatting agent, thickening agent, defoaming agent and the isocyanate curingagent as raw materials. The invention has the advantages of simple paint preparation, low cost, good heat insulation property, being environment-friendly and safe, and the like.