The invention belongs to the technical field of edible fungus cultivation and particularly relates to an efficient disease-preventing auricularia polytricha culture medium and a preparation method thereof. The culture medium comprises, by weight parts, 20-30 parts of broken wood shavings, 10-20 parts of trichoderma anti-mildew agent, 8-20 parts of soy sauce waste residue, 8-15 parts of hull of water chestnut, 8-15 parts of lotus seed hulls, 5-15 parts of banana stem, 1-10 parts of ambrosia trifida, 1-5 parts of rape flower straw and 1-5 parts of cottonseed hull and the like. The method comprises a step (1) of raw material processing, a step (2) of fermentation treatment, a step (3) of charging processing and a step (4) of sterilization processing. The formula design of the culture medium is more suitable for growth of auricularia polytricha, so that auricularia polytricha is bright red compared with fresh agaric, and the quality of the whole auricularia polytricha is improved. Part of raw materials of the culture medium are agricultural and industrial waste, the cost is low, so that the production cost is reduced, a novel handling way is provided for handling the agricultural and industrial waste, and the culture medium is economical and environmentally friendly. The preparation process is simple and easy to popularize.