The invention relates to a thin multifunctional solar reflecting coating and a preparation method thereof. The multifunctional solar reflecting coating is formed by coating multifunctional solar reflecting paint on the surface of a substrate, and the multifunctional solar reflecting paint comprises the following components in weight percentage: 25%-30% of resin system, 0-5% of metallic oxides, 25%-30% of titanium white, 0-2% of talcum powder, 1%-2% of organic bentonite, 2%-3% of corrosion-prevention fillers, 0.5%-1.5% of moist dispersing assistants and 10%-15% of solvents, wherein the resin system is an acrylic resin and curing agent system or a polyurethane modified acrylic resin and curing agent system, the metal oxides are one or more of aluminium oxide, magnesium oxide or zinc oxide, and the corrosion-prevention fillers are one or a mixture of two of aluminum tripolyphosphate or zinc phosphate. In the preparation method, multi-element compounding is carried out by adopting high-reflectivity functional fillers comprising the titanium white, the zinc oxide and the like to realize higher solar reflectivity and hemisphere emissivity of the coating so that the coating has obvious heat-reflecting and cooling effect; the acrylic resin is used as main film forming matter so that the excellent substrate adhesion and the outdoor durability of the coating are realized; and the bottom and the surface of the coating are combined into a whole so that the thickness of the coating is 0.1-0.2 mm, thereby the coating is convenient for construction.