A Chinese medicine composition for treating breast cancer includes Euphorbia kansui, Paeonia lactiflora, Glycyrrhiza uralensis, Taraxacum, Gardeniae fructus, and Hordeum vulgare. A weight ratio of Euphorbia kansui, Paeonia lactiflora, Glycyrrhiza uralensis, Taraxacum, Gardeniae fructus, and Hordeum vulgare in the Chinese medicine composition is 1-2:4-6:2-3:3-5:2-4:2-3. Moreover, a method for treating breast cancer using the Chinese medicine composition is provided, including a step of administering the Chinese medicine composition at an effective dose ranging from 0.1 mg/ml to 10.0 mg/ml to a plurality of breast cancer cells for cultivation. Cell tests have confirmed that the Chinese medicine composition inhibits the activity of the breast cancer cells, achieving the purpose of treating breast cancer symptoms or inhibiting the activity of the breast cancer cells.