The invention discloses a black plaster for treating hyperplasia of mammary glands and a method for preparing the same. The black plaster is mainly used for treating the hyperplasia of the mammary glands, lobules of mammary glands, breast lumps, breast swelling pain and the like, and is prepared from the following raw materials and sesame oil, wherein the main raw materials in weight portion are: 10 to 15 portions of angelica, 6 to 15 portions of radix paeoniae rubra, 6 to 15 portions of rhizoma ligustici wallichii, 6 to 15 portions of radix curcumae, 10 to 15 portions of roasted rhizoma corydalis, 10 to 30 portions of radix salviae miltiorrhizae, 6 to 10 portions of safflower, 3 to 10 portions of boninrousette, 6 to 10 portions of caladium, 10 to 30 portions of bugleweed, 6 to 15 portions of rhizoma cyperi, 6 to 15 portions of radix bupleuri, 10 to 15 portions of radix linderae, 9 to 15 portions of immature tangerine, 6 to 15 portions of hovenia dulcis, 6 to 15 portions of pericarpium trichosanthis, 10 to 30 portions of oyster, 6 to 10 portions of roasted carapax amydae, 3 to 10 portions of brassica alba boiss, 6 to 10 portions of semen vaccariae, 6 to 10 portions of rose, 3 to 10 portions of roasted frankincense, 3 to 10 portions of roasted myrrh, 6 to 10 portions of white batryticated silkworm, 1 to 3 portions of centipede and the like.