A lung occupying lesion is a lesion in the lungs that occupies part of the normal lung position and can cause the tissues surrounding the lungs to be compressed and displaced. There are various causes of lung occupying lesions, mainly including benign or malignant tumors, tuberculosis, and inflammatory pseudotumor. 1. Lung tumor: it refers to tumors occurring in the lung parenchyma and interstitium, and the new organisms formed by its proliferation are mostly occupying mass-like protrusions. Patients should do imaging examination and pathological biopsy as early as possible to diagnose whether they are benign or malignant tumors as well as the types of malignant tumors. 2. Tuberculosis: it is a chronic infectious disease caused by Mycobacterium tuberculosis, the most common tuberculous lesions are proliferative nodules and tuberculous balls, which need to be diagnosed by lung x-ray and sputum Mycobacterium tuberculosis examination. 3. Inflammatory pseudotumor: it is a mass formed by granuloma, mechanization, fibrous connective tissue proliferation and related secondary lesions due to chronic inflammation in the lungs. The clinical manifestation is similar to that of a tumor but the essence is inflammation, with symptoms such as cough and chest pain, which need to be diagnosed by combining with the medical history and imaging examination. After the occurrence of pulmonary space-occupying lesions, doctors need to integrate the patient’s clinical manifestations, medical history, laboratory and other tests to diagnose the disease, and timely treatment to avoid delays in the disease.