The invention provides a dicarboxylic acid heavy calcium carbonate powder fluorescent whitening agent. The dicarboxylic acid heavy calcium carbonate powder fluorescent whitening agent is characterized by having a structural formula 1 shown in the specification. The invention aims to provide the dicarboxylic acid heavy calcium carbonate powder fluorescent whitening agent as well as a preparation method and application thereof, the method is simple, the raw materials are low in price, and the process is green and environment-friendly. The heavy calcium carbonate powder treated by adopting the fluorescent whitening agent provided by the invention has relatively high whiteness and brightness, and relatively good fluidity and dispersity, so that the dicarboxylic acid heavy calcium carbonate powder fluorescent whitening agent is an excellent multifunctional fluorescent whitening agent.