The invention discloses a drug injectant for curing dairy cow mastitis. The drug injectant comprises a specific anti-DP-BM-IgY egg yolk antibody and an extracting solution of a traditional Chinese medicine composition, and relates to an injectant for breasts. The invention further provides a preparation method and application of the drug injectant. The rug injectant provided by the invention has the beneficial effects as followings: the specific anti-DP-BM-IgY egg yolk antibody can be used for killing main pathogenic bacteria of dairy cow mastitis directionally, plays an obvious curative role on various of mastititides, and has the characteristics of stable quality, strong specificity, zero residue and no resistance to drugs; the traditional Chinese medicine composition also has the efficacies of dissipating blood stasis and relieving pain, repelling poison and dispelling pus, cooling blood and relieving swelling, resisting bacterium and eliminating inflammation, and enhancing immunity; the drug injectant for breasts, obtained through combination, can be directly applied into breasts locally, the targeting effect is better, therefore, bioavailability and drug therapeutic effect are improved, the treatment for diseases is more effective and accurate, the whole body toxic and side effects caused by drugs can be lowered, adverse drug reactions are reduced, the use is convenient, the compliance is good, and the safety in use is enhanced.