Patients with a black navel, the common clinical causes are mainly the following: First, the navel due to improper daily cleaning, can cause a large number of bacteria and metabolic waste accumulation, manifested as a black color, accompanied by a large number of mud mass sludge, can be repeatedly cleaned by soapy water or alcohol cotton balls to change the symptoms of a black navel; Second, some patients due to individual differences, can be formed in the navel skin color This is a normal physiological phenomenon and does not require special treatment; Third, if the patient has local ischemia and hypoxia due to occlusion of the blood vessels around the navel, the skin may also appear black. It is often accompanied by a decrease in skin temperature and local pain. The specific location of the arterial stenosis or occlusion can be clarified by vascular ultrasound examination. Interventional treatment can be given as soon as possible to restore arterial blood flow and improve the symptoms of blackening of the navel.