Fly ash had a huge production but it was difficult to utilize. The main component of fly ash was silicon-aluminum compound，which had stable properties. Modification could enhance its activity，and functional coatings was obtained when combine fly ash with functional additives. Using fly ash to prepare architectural functional coatings could not only realize the resource utilization of fly ash，but also reduce the cost of green building materials. Based on the structure and properties，this paper briefly described the application of fly ash in functional building coatings，such as fire retardant coatings，waterproofing coatings，thermal insulation coatings，phase change coatings，anticorrosive coatings and other functional coatings and the role of fly ash in them，and summarized the action mechanism of several coatings，showing that fly ash had a good application prospect in functional building coatings.At the end of this review，we summarized the existing problems of fly ash in functional architectural coatings and prospected the future development direction.