The invention relates to an application of coconut coir in a chrysanthemum grandiflorum medium. The invention relates to the technical field of plant cultivation. According to the invention, coconut coir or a mixture of coconut coir and perlite is adopted as a chrysanthemum grandiflorum growth medium. The invention provides the application of coconut coir in the chrysanthemum grandiflorum medium. According to the invention, with the medium of coconut coir or the mixture of coconut coir and perlite, chrysanthemum grandiflorum growth requirements and needed soil environment are greatly satisfied. The plants are sturdy, stems are thick, and chrysanthemum grandiflorum leaves are dark green. With the application, the medium is breathable and water-permeating, such that plant growth needs are greatly satisfied. According to a cultivation result, the cultivation medium of coconut coir or the mixture of coconut coir and perlite assists in greatly improving chrysanthemum grandiflorum qualities in aspects such as plant height, flowering stem length, flower diameter, and the like, such that cut chrysanthemum grandiflorum ornamental value is improved. Coconut coir is adopted as the chrysanthemum grandiflorum cultivation medium, such that renewable resource utilization rate is greatly improved, and cultivation medium cost is reduced. Therefore, sustainable development of soilless cultivation industry is facilitated.