The invention belongs to the field of traditional Chinese medicines, and discloses a soft capsule for treating hyperplasia of mammary glands and a preparation method thereof. The effective ingredient of the soft capsule is prepared from the following raw materials in parts by mass: polecat, kadsura root-bark, red bartsia, angelica sinensis, opuntia dillenii haw, turtle shell, sea urchin, sargassumthunbergii, concha arcae, akebia quinata, radix bupleuri, pericarpium citri reticulatae, processed black soybeans, fructus aurantii, rhizoma corydalis, rhizoma cyperi, Indian mockstrawberry herb, begonia taiwaniana hayata, borneol, elecampane, fructus amomi, licorice root, beewax, propolis and olive oil. The traditional Chinese medicine is prepared from medicinal materials which are supplementary in efficacy and have mutual gains according to the principle of monarch, minister, assistant and guide, directly acts on breasts, has the effects of promoting blood and qi circulation, resolving hard lumps, soothing the liver, strengthening the spleen, diminishing swelling, relieving pain, regulating chong-ren, improving blood supply of breasts and quickly eliminating breast masses so as to treat hyperplasia of mammary glands.