The invention relates to a traditional Chinese medicine composition for treating cancer and a preparation method thereof. The traditional Chinese medicine composition is prepared from, by weight, 1-12 parts of peach kernels, 1-12 parts of radix angelica sinensis, 1-13 parts of common burreed rhizomes, 1-13 parts of rhizoma curcumae, 1-14 parts of milkvetch roots, 1-14 parts of spreading hedyotis herb, 1-14 parts of barbed skullcap herb, 1-13 parts of the root of common peony, 1-14 parts of kelp, 1-13 parts of manyleaf paris rhizomes, 1-13 parts of leeches, 1-14 parts of seaweed, 1-13 parts of gadflies, 1-11 parts of Chinese blister beetles, 1-13 parts of woodice, 1-14 parts of radix bupleuri, 1-14 parts of black nightshade, 1-14 parts of prunella spike, 1-13 parts of the root of red-rooted salvia and 1-12 parts of safflower. The traditional Chinese medicine composition can treat lung cancer, gastric cancer, carcinoma of the rectum, prostatic cancer, lymph cancer, metrocarcinoma, cervical cancer, esophagus cancer, kidney cancer, carcinoma of urinary bladder, ovarian cancer, pancreatic cancer, leukemia and lupus erythematosus, all of which are cured within one to two courses of treatment, and has a good treatment effect on various kinds of cancer, and cancer does not relapse after being cured.