The invention discloses a waterborne polyurethane emulsion and a preparation method. The waterborne polyurethane emulsion is prepared from the following components in parts by weight: 0.1-0.2 part ofdibutyltin dilaurate, 10-15 parts of polypropylene glycol 2000, 5-8 parts of polyadipic acid-1,4-butanediol ester, 1.3-2 parts of 2,2-dimethylolpropionic acid, 10-15 parts of isophorone diisocyanate,0.5-0.85 part of pentaerythritol, 6-8 parts of acetone, 1.5-2 parts of 1,4-butanediol, 0.8-1.2 parts of triethylamine, 1-2 parts of gamma- aminopropyltriethoxysilane and 55-60 parts of water. The invention also discloses a waterborne polyurethane cooling coating and a preparation method. The waterborne polyurethane cooling coating is prepared from the following components in parts by weight: 90-95parts of waterborne polyurethane emulsion, 0.1-0.5 part of ammonia water, 0-2 parts of color paste, 0.1-0.5 part of a dispersant, 4-6 parts of cooling reflective filler, 0.5-0.8 part of a defoamer, 0.2-0.4 part of a thickener, 0.5-1.5 parts of a flatting agent and 5-10 parts of dipropylene glycol monomethyl ether.