The invention discloses an additive for sterilizing sludge at the bottom of a loach cultivation pond and relates to the technical field of aquaculture. The additive comprises, by weight, 30-40 parts of quick lime, 15-25 parts of mountain flour, 20-30 parts of potassium permanganate powder, 6-8 parts of copper sulfate, 8-10 parts of salt, 6-8 parts of alum, 3-5 parts of tea seed cake, 6-8 parts of croton, 3-5 parts of cassia twig, 4-6 parts of perilla leaf, 2-4 parts of radix sileris, 2-4 parts of radix angelicae dahuricae, 1-3 parts of asarum, 5-7 parts of fistular onion stalk, 3-5 parts of rhubarb, 2-4 parts of chrysanthemum, 2-4 parts of rhizoma anemarrhenae, 2-4 parts of selfheal, 30-40 parts of water, 15-25 parts of starch and 80-90 parts of gelatin. The additive has the advantages that the additive is rich and cheap in raw material, simple in preparation process and high in sterilizing performance, the additive can directly act on the sludge at the bottom of the pond to clean the sludge, loach diseases are minimized, cultivation effect is increased, and cultivation income is increased.