Low oxygen saturation caused by pneumonia but has risen to normal levels after treatment generally indicates that the individual’s condition has been in remission, but to determine the improvement of the disease also needs to be combined with the patient’s symptoms, imaging manifestations and so on. Oxygen saturation is the percentage of the volume of oxygenated hemoglobin bound by oxygen in the blood to the volume of all bindable hemoglobin, i.e., the concentration of oxygen in the blood, which is an important physiological parameter of the respiratory cycle. Oxygen saturation is an important indicator for estimating oxygenation of the lungs. Pneumonia is a common and frequent disease in clinical practice. Since the development of pneumonia affects the lung’s oxygen exchange function, some patients may have low oxygen saturation due to lung ventilation as well as lung oxygen exchange dysfunction. After treatment, if the lowered oxygen saturation has risen to a normal level, some of the uncomfortable symptoms have been relieved, and the imaging indicates a reduction or disappearance of the lesion, then it generally indicates that the pneumonia has been relieved and the condition has begun to improve. Patients with pneumonia are advised to seek prompt medical attention.