The invention relates to a pharmaceutical composition for treating abnormal menstruation. The pharmaceutical composition is prepared from the following raw materials in parts by weight: 15 to 35 parts of Chinese angelica, 10 to 30 parts of semen cuscutae, 10 to 20 parts of ligusticum wallichii, 10 to 20 parts of loofah sponge, 15 to 30 parts of lalang grass rhizome, 10 to 20 parts of bark of Japanese cinnamon, 5 to 20 parts of rheum franzenbachii, 5 to 15 parts of polygonum aviculare, 10 to 20 parts of red sage root, 5 to 15 parts of purslane speedwell, 5 to 15 parts of bitter bamboo leaf, 5 to 15 parts of eupatorium fortune, 10 to 30 parts of edible tulip, 10 to 20 parts of herb of filliform cassytha, 10 to 20 parts of root of Chinese pulsatilla, 5 to 15 parts of begonia fimbristipula, 5 to 10 parts of root of kudzu vine, 5 to 15 parts of cortex fraxini, 10 to 20 parts of globeflower, 10 to 20 parts of semen sinapis, 5 to 15 parts of vallisneria natans, and 5 to 15 parts of pine root. The pharmaceutical composition has the functions of activating blood, regulating menstruation, removing stasis, dissipating binds, nourishing and regulating blood, tonifying middle jiao, and boosting qi, can be used to treat abnormal menstruation and dysmenorrheal caused by various reasons, and does not have any side or toxic effect, and the curative effect is prominent.