Children’s purple mouth is usually associated with physiological causes such as cold environment, and pathological causes such as lung disease and heart disease. 1. Cold environment: If children are in a cold environment and do not take timely measures to keep warm, it may lead to poor local blood circulation, usually manifested in a circle of the mouth purple and other symptoms. 2. Lung disease: children’s purple mouth may also be due to bronchial foreign body, emphysema, pneumonia, natural lung dysplasia and other conditions. It is usually accompanied by coughing and dyspnea. 3. Heart disease: may also lead to children’s mouth circle purple situation, some children also appear face and finger nail end nail bed purple and so on. Children’s mouth purple may also have other causes, it is recommended to go to the hospital in time, complete the examination to determine the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.