The invention discloses a feed additive capable of preventing and treating swine enzootic pneumonia. The feed additive is prepared from the following raw materials: bamboo shavings, curcuma aromatica, thunberg fritillary bulb, common hogfennel root, dandelion, sambucus williamsii hance, trachelospermum jasminoide, lycoris sprengeri, mucuna sempervirens, nandina, zephyranthes candida, hymenocallis littoralis, gendarussa vulgaris, arrhenatherum elatius, rhizoma pinelliae preparata, prunus zippeliana, vermiculite schist seu, clam shell, chitosan and compound enzyme. The feed additive, provided by the invention, capable of preventing and treating the swine enzootic pneumonia is weak acid in taste, and beneficial to promoting appetite, food intake is increased, weight gain is great, the swine enzootic pneumonia is effectively prevented and treated, and incidence is reduced to 0-1%; chitosan is added, nutritional ingredients are enriched, the additive is kept in a stable liquid state, addition amount is small, and application is convenient; and multiple traditional Chinese medicine ingredients are added, compatibility is scientific, pharmacological effects supplement each other, antisepsis and anti-inflammation are realized, no antibiotic or hormone is added, resistance to drugs can not be produced, and immunity is fundamentally enhanced, so that meat quality is delicious, health function of pork is enhanced, no medicament residue is produced, and grade of the pork is obviously improved.