The invention relates to a water culture method for a potted plant. The water culture method for the potted plant is characterized by comprising the following steps: seedling cultivation, cleaning, domestication in the early stage, maintenance with clear water, planting, ultraviolet irradiation, root irrigation maintenance, rapid rooting and normal cultivation. A ceramic ball of a flowerpot of thepotted plant is soaked in irradiation protecting liquid, thus, the ceramic ball fully absorbs and stores the irradiation protecting liquid, and the irradiation protecting liquid is sprayed to a rootsystem of a planted seedling. The water culture method for the potted plant has the advantages that the reasonable dosage of UV-B is adopted to irradiate the potted plant, in combination with the corresponding root system protection and on the premise of not excessively affecting required root system ornamental value of a water culture plant, the potted plant has appearance modes of plant dwarfing, internode shortening and changing of root shoot ratio, and thus, the artistic expression style, which conforms to potted landscape, of the potted plant is obtained; and meanwhile, through strict multi-stage control and in combination with nutrition solutions in different formulas, rapid rooting of the plant is realized, and root rot and slow growth are avoided.