The invention provides a method for preparing a traditional Chinese medicine (TCM) for treating kidney-Yang deficiency type colitis, belonging to the technical field of TCM preparation methods. At present, amikacin is generally adopted to treat kidney-Yang deficiency type colitis and has the defect of big side effects. The method is characterized by comprising the following steps: preparing cordyceps sinensis, desertliving cistanche, actinolite, cortex eucommiae, fleeceflower root, flatstem milkvetch seed, malaytea scurfpea fruit, Chinese holy leaf, common fenugreek seed, walnut seeds, rhizoma drynariae, stalactite, lotus seeds, hippocampus japonicus, sea cucumber, callorhinus ursinus, mulberry, Chinese taxillus herb, China dodder, Chinese dates, Chinese yam, wheat, heterophylly falsestarwort root, black-bone chicken, wild cabbage, longan aril, largehead atractylodes rhizome, white paeony root, American ginseng, angelica, dangshen, sharpleaf galangal fruit, milkvetch root, manyflower solomonseal rhizome, polished round-grained rice, bird's nest, dried finger, glossy ganoderma and liquorice, soaking the above 39 Chinese medicinal materials into water and then decocting with slow fire, thus obtaining the decocted soup, namely the TCM for treating kidney-Yang deficiency type colitis. The method has the following advantages: the prepared liquid TCM has low toxic and side effect and high recovery rate; the course of treatment is short; and the monarch, minister, assistant and guide are matched perfectly.