A dendrobium cultivation matrix and a preparation method thereof are provided; the dendrobium cultivation matrix comprises tea oil processing residue oil tea fruit casing and oil tea dregs, organic inserts, and a biomass polyurethane slow release fertilizer; oil tea dregs after oil, tannin, and saponin extraction, and other ingredient after disinfection treatment are mixed by weight ration as the following: 30-70 of oil tea fruit casing, 10-40 of oil tea dregs, 10-30 of organic inserts, and 10-20 of biomass polyurethane slow release fertilizer; the said ingredients are uniformly mixed, and are filled in a basin or paved on the ground for cultivating dendrobium sprouts; the matrix is good in air permeability, can keep water, is uniform in water absorption, good in intergrouth property, high in survival rate, excellent in dendrobium growth vigor, can provide effective active ingredients for the dendrobium, has bactericidal effect, is hard to mildew, has no pathogen, and insects can hardly hide. The dendrobium harvest time of the dendrobium planted in the matrix can be 1-2 years, and dendrobium polysaccharide content can reach 40-50%.