The present invention provides a nanometer material having a formaldehyde absorbing function, and a preparation method thereof, and relates to the technical field of nanometer materials, wherein the raw materials comprise, by weight, 60-70 parts of a polyurethane polymer material, 9-13 parts of fly ash, 10-14 parts of isopropyl stearate, 5-13 parts of palmitic acid, 2-4 parts of nano-silica, 2-4 parts of nanometer calcium phosphate, 11-17 parts of diatomaceous earth, 10-16 parts of active carbon powder, 3-7 parts of a stabilizer additive, 0.5-0.7 part of a coupling agent, 0.2-0.4 part of an antioxidant, and 0.2-0.8 part of a foaming agent. The preparation method comprises: (1) weighing raw materials, (2) preparing a mixture a, (3) preparing a mixture b, (4) preparing a mixture c, and (5) feeding into a mold, and molding. The prepared nanometer material of the present invention has advantages of high strength, good thermal insulation performance, and formaldehyde absorption.