Dark and blue face often consider heart disease such as congenital heart disease, coronary heart disease, etc., but also consider respiratory diseases such as chronic obstructive pulmonary disease, pulmonary embolism, etc., but also due to individual differences in the presence of facial changes, need to be specifically analyzed. 1. Heart disease: To observe whether the patient’s skin color is dark, whether there is lack of oxygen or cyanosis, heart disease patients due to heart pumping dysfunction or narrowing of the heart blood vessels, etc., will cause blood and oxygen supply is insufficient, manifested as cyanosis or even black. 2. Respiratory diseases: when patients suffer from chronic obstructive pulmonary disease, chronic bronchitis and other respiratory diseases, the structure and function of the lungs will be damaged, the lungs ventilation and ventilation function is impaired, so the oxygen content in the peripheral blood is reduced, the patient has a cyanosis and black performance. If there is a blue and black face to exclude hereditary factors, long-term sun exposure and other conditions, if there is a pathological state, the patient should immediately go to the hospital, early formal treatment, do not delay the condition.