Elderly people have frequent coughing with phlegm at night, and the possible clinical causes are caused by bronchial dilatation, chronic obstructive pulmonary disease, bronchial asthma and so on. 1. Bronchial dilatation: this disease refers to the irreversible expansion of bronchial tubes and fine bronchial tubes caused by repeated infections and inflammatory reactions in the airways, and its typical symptoms are coughing up a large amount of purulent sputum, coughing, hemoptysis, etc., and the coughing symptom is mostly seen in the night time as well as in the morning. 2. Chronic Obstructive Pulmonary Disease (COPD): This is a lung disease that causes dyspnea due to restricted airflow, with typical symptoms of shortness of breath or dyspnea during activity, which can be relieved after rest. The typical symptoms are shortness of breath or dyspnea during activities, which can be relieved after resting. With the progress of the disease, there will be coughing, coughing up sputum and respiratory failure, etc., and the sputum is white and plasma-like, and the coughing symptom mostly appears in the morning or at night. 3. Bronchial asthma: people with this disease in the night respiratory sensitivity will increase, and therefore by the cold air or the external environment of the stimulus may appear violent cough. Elderly people coughing frequently at night with phlegm can also be seen in heart failure, nasal secretion reflux stimulation of cough and gastroesophageal reflux stimulation of cough and so on, it is recommended that the existence of the relevant conditions of the crowd should be to the hospital as soon as possible to accept the examination and targeted treatment.