Coughing up yellow sputum in the morning can be caused by a variety of respiratory diseases, common causes include upper respiratory tract infections, bronchial dilatation, staphylococcus aureus pneumonia and so on. 1. Upper respiratory tract infection: bacterial infection caused by upper respiratory tract infection, under the stimulation of inflammation will lead to increased secretion in the throat area, can appear in the morning to cough up yellow sputum. 2. Bronchial dilatation: when the bronchial tubes are repeatedly infected, the destruction and deformation of the airway structure can cause obstruction or expansion of the airway, and the main clinical manifestations of the patients are chronic cough, coughing up a large amount of yellowish sputum and repeated hemoptysis. 3. Staphylococcus aureus pneumonia: the disease starts sharply with chills, high fever, shortness of breath, cyanosis, chest pain, coughing yellow pus sputum or pus and blood sputum, etc. In severe cases, there is peripheral circulatory failure. Severe cases have peripheral circulatory failure, i.e. infectious shock. Coughing up in the morning with yellow sputum can also be seen in other diseases, it is recommended to timely to the regular hospital, clear cause, standardized treatment under the guidance of the doctor, so as not to delay the condition.