The invention relates to a pharmaceutic preparation for livestock, comprising silymarin, or silymarin and antibiotics, wherein the antibiotics is selected from beta-lactams, quinolones, tetracyclines, sulfonamides, chloramphenicols or macrolide antibiotics. The test shows that the sensitivity of the antibiotics to the bacterium can be effectively improved, and the drug resistance of the antibiotics to the animal pathogeny can be reduced according to the invitro bacteriostasis test result and the animal invivo test result when the silymarin with a certain concentration is jointly used with the antibiotics, so that the animal bacterial disease can be effectively controlled, the usage amount of the antibiotics in the animal disease can be reduced, the breeding cost can be reduced, the breeding income can be increased, and the safety of the animal-derived food can be improved.