Pneumonia is classified as lobar pneumonia, lobar pneumonia, and interstitial pneumonia, and either type of pneumonia can manifest as lung shadows in the lungs. The lung shadows are mainly due to alveolar bruising and congestion caused by massive alveolar exudation during pneumonia, which can be indicated by changes in the lung shadows in imaging, which can be patchy, cloudy or flocculent. If the change is solid, it may indicate lobar pneumonia; if it is lobar pneumonia, it may appear as cloudy or flocculent changes; if it is caused by interstitial pneumonia, it may indicate bilateral lower lung fibrosis and lattice-like or honeycomb shadow changes. In conclusion, once pneumonia occurs clinically, chest imaging should be given, and once it suggests the presence of shadows in the lungs, the specific cause of the pneumonia should be further clarified in conjunction with the patient’s basic condition, blood count, and other biochemical tests for targeted treatment.