The invention discloses an ultramicro traditional Chinese medicine for preventing and treating lactation reduction and redness and swelling of breasts of dairy cows. The ultramicro traditional Chinese medicine comprises raw materials in parts by weight as follows: 25-32 parts of dandelions, 18-22 parts of weeping forsythia, 15-25 parts of baical skullcap root, 25-34 parts of cowherb seeds, 18-22 parts of beautiful sweetgum fruits, 8-13 parts of uniflower swisscentaury root, 18-22 parts of Chinese angelica, 8-13 parts of rhizoma chuanxiong, 6-11 parts of bighead atractylodes rhizome, 9-14 parts of frankincense, 6-12 parts of myrrh and 8-11 parts of Chinese honeylocust spines. The ultramicro traditional Chinese medicine has the functions of treating both symptoms and root causes, and can be used for directly inhibiting or killing pathogenic bacteria of mastitis or inhibiting or killing pathogenic bacteria through improvement of body immunity; the medicine formula adopts the principles of heat and toxic material clearing, antisepsis, anti-inflammation, menstrual flow promotion, blood circulation promotion, swelling and pain elimination, collateral activation and lactation promotion, has functions of tonifying qi, raising yang and strengthening body resistance to dispel pathogenic factors, is effective and has a high cure rate, the milk quality of the dairy cows is improved, and the milk amount is remarkably increased. The ultramicro traditional Chinese medicine has controllable quality and the drug dependence is eliminated.