The blackened blood vessels under the tongue are usually the sublingual veins, normal structure; if there is too much blood stagnation, the venous pressure is higher, resulting in part of the blood penetrating outside the blood vessels as well as the subcutaneous tissue, which will also cause the patient to have the performance of blackened and purple sublingual blood vessels. Clinically, the following can be done: First, it is recommended that patients have their blood drawn for lipids and blood viscosity, most of them may have high blood lipids and high blood viscosity, and if they have high blood lipids, it is recommended to take lipid-lowering drugs for lipid-lowering treatment. Secondly, for such patients, pay attention to the combination of work and rest, usually eat more vegetables and fruits, avoid overeating, do not eat too greasy, spicy, stimulating things, usually pay attention to a light diet, eat nutritious and easy to digest things.