The invention provides a preparation method of a composition for treating rumen indigestion, which comprises the following steps: A. cleaning active pharmaceutical ingredients, including Fructus Forsythiae, phellodendron bark, rhubarb, hawthorn, picrorhiza rhizome, mirabilite, alcoholic rhizoma anemarrhenae, alcoholic golden cypress, medicated leaven, moleplant seed, fructus aurantii, dried orange peel, bush-cherry seed, honied radix astragali, dangshen, amomum fruit, pawpaw, tuckahoe, agilawood, Chinese yam, figwort and licorice; B. moisturizing; C. decocting; D. adding 95 wt% ethanol into the concentrated juice obtained in the step C to precipitate water-soluble impurities, adding an additive, uniformly dissolving, and filtering to obtain a filtrate; and E. heating the filtrate in the step D, carrying out ultraviolet sterilization to obtain a traditional Chinese medicine liquor, and preparing a fermenting material: cutting the straws into short grass which is 2-3cm long or so, uniformly spraying 1kg of 5 wt% sodium hydroxide solution onto every 100kg of straws while stirring, covering a plastic film, and fermenting at room temperature for 24 hours to obtain the saltish fermenting material, wherein the weight ratio of the traditional Chinese medicine liquor to the fermenting material is (5-8):(50-100). The composition is simple in proportioning and convenient to use, and is used for clearing away heat and toxic material, activating blood circulation to dissipate blood stasis, promoting circulation of qi and to relieve pain, strengthening the spleen, stimulating the appetite, strengthening the middle-jiao, invigorating qi, removing heat from the blood and promoting salivation.