The invention discloses a water-soluble fluorescent whitening agent for coarse whiting powder. The water-soluble fluorescent whitening agent for the coarse whiting powder is of the following structural formula 1 as shown in the description. The invention aims at providing the water-soluble fluorescent whitening agent for the coarse whiting powder as well as a preparation method and application thereof; the method is simple; the prices of raw materials are low; a process is green and environment-friendly. By adopting the fluorescent whitening agent provided by the invention, calcium carbonate powder can be effectively whitened and brightened; the fluorescent whitening agent also has a surface modification effect at the same time.