If a baby has pneumonia, the doctor will recommend a chest X-ray according to the child’s specific situation, in order to clarify whether pneumonia, bronchitis, or other infectious diseases of the lungs. Baby pneumonia clinically prone to cough, cough sputum, high fever and even dyspnea, the examination can be heard in the lungs with fine wet rales, routine blood tests if the bacterial infection can suggest that the total number of white blood cells, neutrophils, calcitoninogen, C-reactive protein and so on significantly higher. If the infection is viral, the total number of leukocytes may be decreased or lymphocytes may be increased. Chest imaging can be used to accurately assess the severity of the pneumonia and whether it is unilateral or bilateral. If combined with a bacteriologic culture, it can be determined whether the infection is caused by a common bacterial infection or by Staphylococcus aureus pneumonia. In conclusion, chest radiographs are still accurate for pneumonia in babies, except for more specific infections, such as tuberculosis infection and Staphylococcus aureus infection, which need to be further clarified by combining with imaging and bacteriologic tests, especially chest CT, to find out the status of the lung infection, so that the treatment plan can be adjusted.