The invention belongs to the technical field of seaweed cultivation, and relates to a seaweed cultivation method. Natural seawater is contained in a seawater tank, and the temperature and the ultraviolet lamp irradiation are controlled to conduct disinfection treatment for standby application; selected and collected seed seaweeds are washed, disinfected and dried, then conventional culture media are selected according to different seaweed types, temperature control and dim-light static cultivation are carried out, and then enzymolysis or direct cultivation is carried out; after to-be-cultivated somatic cells, to-be-cultivated gametophytes or to-be-cultivated callus mature, bolting-silk filtering, sectioning processing and/or centrifugal collecting are carried out, the somatic cells, the gametophytes or the callus are placed into the culture media according to the requirements of different kinds of seaweeds, the temperature, the illumination and the osmotic pressure are controlled for cultivation, and the somatic cells, the gametophytes/sporophores and the callus of the seed seaweeds are attached to the silk net faces in the culture media; silk nets are then manually scattered into the offshore or the tidal zone to conduct conventional seawater cultivation. The seaweed cultivation method is simple in technology, low in cost, convenient to operate, short in seedling growing time, good in cultivation effect and high in cultivation yield, and manpower is saved.