The invention relates to the field of animal drugs, in particular to traditional Chinese medicine powder for preventing and treating cow subclinical mastitis, and aims to solve the problems that the cow subclinical mastitis is not easy to detect and does harm to people. The technical scheme to solve the problems is as follows: the traditional Chinese medicine powder is prepared from the following components in part by weight: 47-53 parts of honeysuckle, 57-63 parts of fructus forsythia, 57-63 parts of dandelion, 27-33 parts of astragalus membranaceus, 27-33 parts of angelica sinensis, 27-33 parts of tetrapanax papyriferus, 40-45 parts of trichosanthes kirilowii, 7-53 parts of caulis akebiae, 20-25 parts of liquorice, 57-63 parts of cowherb seed, 60-65 parts of herba violae, 47-53 parts of kelp, and 57-63 parts of ligusticum wallichii. The preparation method of the traditional Chinese medicine powder comprises the steps of cleaning, air-drying, uniformly mixing and smashing the raw material components. The traditional Chinese medicine powder has the effects of clearing away heat, removing toxicity, diminishing swelling, removing stasis, activating blood, removing blood stasis, preventing poison from harming viscera, eliminating heat, promoting urination, stimulating the menstrual flow, promoting lactation, tonifying qi and benefiting spleen, and is antisepsis and anti-inflammation, thereby achieving remarkable effect of preventing and treating the cow subclinical mastitis.