The invention relates to a medicine for treating aplastic anemia. The medicine comprises the following bulk pharmaceutical herbs in parts by weight: 40-50 parts of donkey-hide gelatin, 40-50 parts of rehmannia root, 40-50 parts of suberect spatholobus stem, 40-50 parts of astragalus root, 40-50 parts of lotus rhizome node, 40-50 parts of Chinese angelica, 40-50 parts of hairy asiabell root, 40-50 parts of white paeony root, 40-50 parts of Chinese wolfberry root-bark, 40-50 parts of dwarf lilyturf tuber, 40-50 parts of endothelium corneum gigeriae galli, 40-50 parts of dock root, 25-36 parts of Chinese magnoliavine fruit, 25-36 parts of liquorice, and 55-65 parts of ophicalcite. A preparation method of the medicine for treating the aplastic anemia comprises the following process steps of: (1) weighing Chinese medicinal herbs in parts by weight as required, cleaning the Chinese medicinal herbs, soaking the Chinese medicinal herbs for 3 hours, then, adding water 10 times that of the total weight of the Chinese medicinal herbs, decocting for 50 minutes, filtering and preserving decoction for later use; (2) concentrating the decoction obtained in (1) into thick paste, drying the thick paste, and crushing the dried thick paste into fine powder to obtain the medicine for treating the aplastic anemia; and (3) packing the medicine obtained in (2) into capsules in the specification of 0.5g per capsule. The medicine has a very good curative effect of treating the aplastic anemia.