2 and a half year old baby does not have a fever, no runny nose, a sudden cough with phlegm, can be seen in respiratory tract infections, tracheal foreign body and other cases, specific need to analyze and judge according to the baby’s situation. 1. Respiratory tract infections: such as acute bronchitis, bronchopneumonia, mostly caused by viruses (such as respiratory syncytial virus), bacteria (such as Streptococcus pneumoniae) or Mycoplasma pneumoniae and other infections, inflammation of the mucosa of the lower respiratory tract or the alveoli, secretions can be produced, coughing with sputum symptoms, some babies can be accompanied by wheezing and other symptoms. 2. tracheal foreign body: this kind of baby has abnormal choking history, may appear suddenly cough symptoms, foreign body stimulation of the local mucosa, may produce abnormal secretion, appear the above performance, often repeated cough, not easy to cure. 3. Other: cough is the body’s normal protective mechanism, such as the baby morning phenomenon, often through the cough can be discharged from the respiratory tract secretions, often cough phlegm symptoms are mild, is a normal physiological phenomenon. 2 and a half year old baby does not have a fever, not runny nose, a sudden cough with phlegm, there may 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, under the guidance of the doctor to give targeted treatment or treatment.