Children with mycoplasma pneumonia three days after discharge from the hospital sputum turns yellowish green may be pneumonia recurrence as well as bronchitis and other causes. 1. Pneumonia recurrence: when bacteria invade the human respiratory tract, it will stimulate the body’s immune system, so that the immune cells in the respiratory tract tissues to gather, kill and phagocytosis of bacteria, when the cells are necrotic, these bacteria will produce inflammatory secretions, the formation of yellow sputum. 2. Bronchitis: Bronchitis may be accompanied by bronchial dilatation, resulting in fibrosis of the bronchial mucosa, usually with a large amount of yellow or pus sputum. Pneumonia after the decline in resistance, there may be infected bronchitis. Children with mycoplasma pneumonia three days after discharge from the hospital sputum becomes yellow and green, there may also be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.