Sputum is a kind of mucus secreted by the airways after being stimulated. Sputum contains dust, dust, bacteria, viruses, cells in the respiratory system and lungs, necrotic tissues, and purulent secretions that are inhaled in the lungs. The black flocculent stuff inside the sputum is clinically visible for many reasons, the more common reason is due to long-term smoking, or work or living environment is relatively dusty, air pollution is more serious, stay in such an environment will be inhaled to the airway, these dust will be deposited and attached to the mucous membrane wall of the respiratory tract, eliminated through the sputum, black. In addition, it is the long-term inflammation in the chronic respiratory tract, not completely recovered and cured, the airway mucosa has old bleeding lesions, these blood clots will collect in the airway, and when the cilia constantly move upward and are expelled through the sputum, black flocculent material will appear. Clinically, X-rays, or CT of both lungs can be taken, and black flocculent material can be taken, and pathogen cultures and drug sensitivity tests can be done to clarify the cause and condition.