Leech has the efficacy of breaking blood and promoting menstruation; it can be used for blood stasis and menstrual closure; the dosage is 1-3g at a time or as directed by the doctor. Leech is the dried whole of leech of family Hirudinidae, with bitter and salty taste, flat nature and slight toxicity. It can break blood circulation, expel blood stasis and eliminate symptoms, and is often used in the treatment of blood stasis and menstrual occlusion, obstruction in the abdomen, lumps in the abdomen, hemiplegia, bruises, etc. Due to its toxicity, leech can be used in the treatment of the following conditions: a single dosage – g or as prescribed. Due to its toxicity, the dosage should be in strict accordance with the doctor’s instructions; prohibited for pregnant women. Usually, leeches are in the form of irregular flat lumps, dark brown on the back, brownish yellow to brown on the belly, with a slight fishy odor, and should be avoided if its properties are found to have changed before use. Patients need to take it after the professional Chinese medicine practitioners to identify the prescription, not blindly use on their own.