The invention discloses a floating seedling cultivating method for pierisformosa. Pierisformosa seedling cultivating is completed through the steps of building a floating seedling cultivating pond, processing seeds, preparing a seedling cultivating matrix, selecting and disinfecting a floating disc, loading the disc, sowing the seeds, setting a floating water body, applying a floating seedling cultivating nutrient solution, preventing and treating moss, hardening seedlings, carrying out transplanting and the like. According to the floating seedling cultivating method, varieties of the floating seedling cultivating matrix and the size of particles of the matrix are set, and the specific operation steps for the pH value and the temperature of the floating water body, the ratio of the matrix, the water content of the matrix and seed sowing and moss retraining are strictly regulated, so that the emergence rate of pierisformosa is greatly increased, the emergence rate can reach 90% or above, the percentage of seedling emergency is quite high, and the germination rate can be improved by 35% or above and the emergency rate can be improved by 45% or above compared with a conventional seedling cultivating method; the uniformity of cultivated seedlings is high, root systems of the seedlings are developed and robust and grow robustly, few plant diseases exist, and no weed grows.