The invention discloses a weather-resistant coating and a preparation method thereof. The weather-resistant coating comprises the following components in parts by weight: 10-40 parts of water, 10-50 parts of an acrylic acid emulsion, 20-70 parts of packing, 0.1-1 part of an ultraviolet absorbent, 1-30 parts of nano zinc oxide, 0.1-5 parts of a dispersing agent, 0.1-5 parts of a wetting agent, 0.5-5 parts of a defoaming agent, 0.1-5 parts of a leveling agent, 0.1-5 parts of a thickening agent and 0.1-5 parts of a preservative. The invention further discloses a preparation method of the weather-resistant coating. By adopting the weather-resistant coating, the ultraviolet light shielding property of a coated layer can be protected, meanwhile, the density of the coated layer can be greatly increased, the water resistance property of the coated layer can be improved, and thus the water movement prevention property of a pre-installed and inverted adhered waterproof roll can be improved; and in addition, the tensile strength and break elongation of the coated layer can be remarkably improved, and thus the waterproof property of the pre-installed and inverted adhered waterproof roll can be improved.