The present invention discloses a fermentation method of potato residues. The method comprises the following steps: (1) seed koji preparing: wheat bran and water are fully and evenly mixed at a weight ratio of (1-2):(1-2), the mixture is sub-packaged into each of culture dishes, the sub-packaged mixture is subjected to a high-pressure sterilization, when the temperature of the materials is lowered to 50-60 DEG C, yeasts are inoculated, and the materials are cultured at 32-35 DEG C for 3-4 days; (2) according to the parts by weight: 9-10 parts of crushed potato residues and 1-2 parts of wheat bran are mixed; and (3) fermenting: an appropriate amount of water is added into the crushed potato residues, the mixture is rolled evenly, and the rolled mixture is put into a steaming basket to be steamed using high heat for 30-40 minutes. The fermentation method can increase the protein amount of fermentation substrate, reduce the amount of crude fibers, and improve the feed palatability and digestion utilization, and is small in scales, easy for operations, less in investment, fast in effects, suitable for processing and utilization of farmers, and a new way for developing rural feed resources.