The invention provides a traditional Chinese medicine composition for treating ulcerative colitis, and a preparation method thereof. The composition of the traditional Chinese medicine for treating ulcerative colitis is prepared by mixing the components in parts by weight as follows: 10-30 parts of chrysanthemum, 15-25 parts of pericarpium citri reticulatae, 10-30 parts of radix curcumae, 10-30 parts of hawthorn, 5-15 parts of liquorice, 15-25 parts of fructus amomi, 20-40 parts of endoconcha sepiae, 5-10 parts of coptis chinensis, 2-8 parts of gizzard pepsin, 15-25 parts of mangnolia officinalis, 30-50 parts of Chinese-date flesh, 10-20 parts of bletilla striata, 20-30 parts of rhizoma corydalis and 25-35 parts of propolis. The composition of the traditional Chinese medicine has the benefits that the composition is reasonable; a synergistic effect of every component is achieved; the composition of the traditional Chinese medicine has the functions of clearing away heat, drying dampness, tonifying spleen, nourishing stomach and the like, is good in curative effect, can take effect quickly and achieve the effect of treating both symptoms and root causes, and can be prepared easily; the components can be mixed more uniformly step by step; the composition of the pure traditional Chinese medicine is free from pollution, drug residues and drug resistance, low in cost, wide in material drawing range, high in availability and remarkable in curative effect; and superfine grinding is achieved.