The invention discloses a gray heat-reflecting cooling coating, an application thereof in asphalt pavements, and a preparation method of the coating. The coating comprises, by weight, 100 parts of a water-based polyurethane polymerization emulsion, 1-20 parts of a metal oxide mixed phase pigment, 2-15 parts of a heat reflection filler, 1-10 parts of inorganic hollow micro-particles, 0.1-5 parts ofa dispersant, 1-30 parts of a flatting agent, 0.1-5 parts of a defoaming agent, 1-10 parts of a leveling agent, 3-20 parts of a plasticizer, 0.2-6 parts of an anti-sagging agent and 0.05-2 parts of agel. The gray heat-reflecting cooling coating can reflect 80% or above of near-infrared lights, can be applied to the surfaces of pavements, house buildings and various steel structures, and can reduce the temperature by 10-20 DEG C in summer. When the coating is used for asphalt pavements, the pavement temperature can be greatly reduced, and damages such as ruts and burst caused by high temperature are reduced; and the coating is especially used for urban main roads, the urban heat island effect can be effectively relieved, and the living environment is greatly improved.