The effects of leeches are to break blood and remove blood stasis and to open the meridians. Clinical application of leech can treat stasis of blood, such as absorption of hematoma after cerebral hemorrhage; for cerebral thrombosis, it can be of great use to improve circulation, especially to protect brain tissue from destruction. Also, leech can lower serum urea nitrogen and creatinine levels, which has a good protective effect on the kidneys and can improve blood circulation to the kidneys and improve some kidney functions. Its treatment is mainly by injection solution. Leech can also lower blood lipids, as well as reduce or correct atherosclerosis of blood vessels and improve blood supply to the heart, especially for patients with coronary heart disease, and leech can significantly improve their symptoms. Leeches also have very obvious anticoagulant properties, which are also of great benefit to patients with angina pectoris. The action of leech is contraindicated, mainly in patients with bleeding, and is not suitable for application of leech, otherwise it will increase the risk of bleeding.