Purple tongue can be seen clinically as cyanotic tongue, cyanotic tongue often indicates stagnation of blood in the body in TCM clinical practice, which needs to be given sufficient attention, and when the tongue is purple, it mostly represents potential or chronic diseases that have occurred. If the tongue is purple, it can be partly or fully blue-purple, such as purple tongue is less suggests heat and Yin, need to clear heat and nourish Yin, the tongue is blue-purple, thin white tongue moss suggests cold evidence, need to warm Yang to drive away cold, such as the tongue is blue-purple tongue moss with dry suggests serious heat evidence, need to clear heat and dispel fire, the tongue is blue-purple tongue moss moist suggests cold and damp evidence, need to warm Yang to benefit damp treatment. In clinical practice, it has been found that a purple tongue for a long time is often a sign of early-stage or mid- to late-stage cancer, which requires special attention. The most common clinical causes of purple tongue are blood stasis and blood blockage, common diseases such as dysmenorrhea, amenorrhea, lupus erythematosus, coronary heart disease, etc. Therefore, if you have purple tongue for a long time, you should consult a doctor in time to avoid aggravation of the disease. Clinical data show that a purple tongue indicates a potential chronic disease in the body and should be prevented from inducing serious diseases by stagnation of blood in the body. Diet should be based on a light diet, avoid stimulating food, do not eat greasy food, and should also strengthen exercise.