Cough with black sputum may be caused by long-term smoking, environmental factors or some disease factors. 1. Long-term smoking: If you smoke for a long time, the smoke will irritate the airway mucosa, damage the airway mucosa, make the mucosa damage necrosis and shedding, the shedding tissue will be discharged with the sputum, so there is the phenomenon of coughing with black sputum; 2. Environmental factors: If you live in a polluted environment with black dust in the air, inhaling such air for a long time will easily lead to coughing with black sputum; 3. Disease factors: Cough with sputum can also be caused by hemoptysis, such as the presence of bronchial dilatation, tuberculosis, lung tumors, as well as severe pneumonia and other phenomena may have hemoptysis. If the blood stays in the airway for a long time, it will turn black after the reaction, so the phenomenon of coughing with black sputum appears. Cough with black sputum is recommended to go to the respiratory medicine department of a specialized hospital to find out the exact cause. If it is caused by a disease, it must be actively treated, so as not to jeopardize the health of the body.