NOVELTY - Chinese medicinal disinfecting agent is prepared by (a) preparing Chinese medicinal composition, (b) adding ethyl alcohol to Chinese medicinal composition, and performing ultrasonic-assisted extraction for 3 times, (c) filtering extracts, mixing filtrates, and concentrating mixture, (d) adding water to filter residues, performing ultrasonic extraction, filtering extracts, and mixing filtrates, (e) uniformly mixing e.g. product obtained in step (c) and propylene glycol, and adding product obtained in step (d), and (f) precipitating mixture and obtaining supernatant.    USE - The Chinese medicinal agent is useful for disinfecting dairy farm (claimed).    ADVANTAGE - The method is environmentally-friendly, improves stability of the product which does not has bad influence on cows, and does not leave medicinal residues. The product delays development of drug resistance.    DETAILED DESCRIPTION - Chinese medicinal disinfecting agent is prepared by (a) preparing Chinese medicinal composition by accurately weighing and crushing 26-34 parts Chinese gall, 25-30 parts herba houttuyniae, 23-27 parts rhizoma coptidis, 22-26 parts baikal skullcap root, 21-25 parts dyer's woad leaves, 20-22 parts common Andrographis herb, 20-25 parts radix isatidis, 20-23 parts wild Chrysanthemum flower, 18-22 parts Ginkgo, 15-20 parts grassleaf sweetflag rhizome, 12-16 parts Magnolia officinalis, 10-15 parts thyme, 8-12 parts loosestrife and 5-10 parts licorice, respectively to obtain respectively powders having 40-60 mesh size, and uniformly mixing the powders, (b) adding 5-10 times ethyl alcohol (60%) to the Chinese medicinal composition, performing ultrasonic-assisted extraction at 200 W and 60-80 degrees C for 30-50 minutes for 3 times, (c) filtering extracts obtained in step (b), mixing filtrates, storing mixture in refrigerator for 24-30 hours, and concentrating the mixture at 60-80 degrees C until relative density of mixture reaches 1.1-1.2, (d) adding 3-5 times water to obtained filter residues, subjecting obtained mixture to ultrasonic extraction at 85-95 degrees C for 1-2 hours for 3 times, cooling extracts to room temperature for 1-2 hours, filtering extracts, and mixing filtrates, (e) uniformly mixing product obtained in step (c), Tween 80 (RTM: Polysorbate 80) and propylene glycol in a ratio of 1:1:3, and then adding product obtained in step (d) to obtained mixture, and (f) precipitating the mixture and obtaining supernatant which is product.