The invention discloses waterborne polyurethane thermal-insulating sound-absorbing coating and a preparation method thereof. The waterborne polyurethane thermal-insulating sound-absorbing coating comprises a polyurethane prepolymer, N-hydroxymethyl acrylamide, phthalic acid dibutyl ester, a zirconium-aluminic acid ester coupling agent, rutile titanium dioxide, methylsilicone oil, a mixed solvent and a sound-absorbing material. The preparation method comprises the following steps: dissolving every 1 kg by weight of N-hydroxymethyl acrylamide in 2 kg of 50-70% ethanol in volume concentration, mixing with the polyurethane prepolymer in a reaction kettle, enabling the components to react for 1 hour at 80-150 DEG C, and adding the zirconium-aluminic acid ester coupling agent to continuously react for 2-5 hours; subsequently adding the phthalic acid dibutyl ester, rutile titanium dioxide, methylsilicone oil, mixed solvent and sound-absorbing material, and uniformly mixing, thereby obtaining a waterborne polyurethane thermal-insulating sound-absorbing coating product. The waterborne polyurethane thermal-insulating sound-absorbing coating can insulate heat and absorb sound, and is good in chemical resistance, good in temperature resistance, good in weather resistance, long in film service life, free of toxicity or smell, safe and environment-friendly and good in sound absorption effect.