The invention discloses a seedbed for dendrobium polyploid and a preparation method of the seedbed, and relates to the technical field of plant seedbeds. The seedbed provided by the invention comprises the following components in parts by weight: 40-60 parts of fruit peel, 20-40 parts of sugarcane leaves, 15-30 parts of poultry manure, 10-15 parts of river bottom filtered mud, 12-20 parts of an attapulgite-lavender essential oil complex, 5-10 parts of humus, 5-10 parts of dipotassium hydrogen phosphate, 1-5 parts of magnesium sulfate, 5-10 parts of zinc sulfate, 1-5 parts of peanut bran, 1-2 parts of ferrous sulfate heptahydrate, 2-4 parts of borax, 3-6 parts of calcium superphosphate and 1-5 parts of an deodorant. The preparation method comprises mixing materials, carrying out first-stagefermentation and carrying out second-stage fermentation. The seedbed provided by the invention has good water permeability and air permeability, so that the seedbed bed is not easily hardened, the propagation speed, the survival rate and the effective component content of the dendrobium polyploid can be obviously improved, and the incidence of diseases and insect pests is reduced.