A cough with phlegm in a two-month-old baby is generally less likely to heal on its own and needs to be treated on a case-by-case basis to avoid aggravating the condition. Coughing with phlegm in babies may be caused by respiratory infections such as bronchitis and pneumonia, which are generally associated with infections such as viruses, bacteria, mycoplasma, chlamydia and fungi caused by exposure to cold. Also, allergy to certain factors such as cold air, pollen, dust mites, etc. cannot be excluded and may be related to rhinitis and sinusitis. If the coughing is not accompanied by fever and shortness of breath, the child should be given proper care, adjust the diet, such as giving light, easily digestible food, and apply coughing and phlegm-relieving drugs and pat the back. If the cough is accompanied by other symptoms such as fever, lack of energy and nasal agitation, the child should go to a regular hospital in time and receive symptomatic treatment under the guidance of a specialist to avoid the prolongation of the disease due to mismanagement, which may endanger the life and health of the child. As babies are young, their resistance is poor and their immune system is not yet well developed, so parents should not wait for the disease to heal itself, but seek medical attention in time. At the same time, pay attention to the baby’s clothing, to prevent cold and wind.