The invention relates to the technical field of coatings, and provides a sand-in-water multicolor coating and a preparation method thereof. The sand-in-water thermal insulation coating provided by theinvention comprises base paint, a protective glue solution and a continuous phase, wherein the base paint is prepared from the following components in parts by weight: 0.6-0.65 part of cellulose, 0.5-1 part of inorganic color paste, 40-50 parts of quartz sand, 3.5-4 parts of a filler, 2.5-3 parts of acrylic emulsion, 10-11 parts of silicon dioxide dispersion liquid, 0.3-0.4 part of protective glue and 30-36 parts of water. The sand-in-water multicolor paint has good stability and long storage period, meets the requirements of inorganic paint standards for buildings on the content of macromolecular organic matters, and can meet the requirements of energy conservation, environmental protection, safety, fire prevention and the like, so that a formed paint film has rich and full patterns, high simulation degree and vivid stone effect.