A purple tongue is a cyanotic tongue, suggesting blood stagnation in the organism, with stagnant blood staying in the body. Patients with this tongue image often have organic diseases, such as coronary atherosclerotic heart disease, pulmonary heart disease, vasculitis, diabetes, vasculitis, etc., because these diseases are characterized by high blood viscosity and slow blood flow. Poor blood flow tends to form blood stasis, which is reflected in the tongue as a blue tongue. The greenish purple tongue also indicates hyperthermia, such as poisonous insect bites, poisonous snake bites, food poisoning, alcohol poisoning, etc., which may be seen on the tongue. In addition, extreme pain caused by cold and damp paralysis may also appear as a greenish purple tongue. Therefore, when a cyanotic tongue is seen clinically, the patient must be asked carefully about the accompanying symptoms and not to generalize, thus affecting the subsequent treatment.