Multiple lung nodules belong to the description of chest imaging examination, which may be malignant, such as metastatic lung cancer, and can also be seen in benign diseases, such as cornual tuberculosis, pneumoconiosis, autoimmune diseases, etc. 1. Metastatic lung cancer: refers to malignant tumors in any part of the body that have metastasized to the lungs through various metastatic modes. Most of the metastatic lung cancers are multiple foci in both lungs, with different sizes and uniform density. 2. Milquetoast tuberculosis: after tuberculosis mycobacterium infection, it spreads to the lungs through blood source, and diffuse nodular image in the lungs can appear. It is often accompanied by systemic symptoms such as low-grade fever, fatigue and night sweats. 3. Pneumoconiosis: a systemic disease with diffuse fibrosis of lung tissue as the main cause due to long-term inhalation of harmful dust and retention of dust in the lungs. Small round shadows appear in the lung fields, and the small shadows gradually increase, become larger and more intensive. 4. Autoimmune diseases: such as rheumatoid arthritis, systemic lupus erythematosus, etc., whose autoantibodies may damage the connective tissues of the lungs, causing multiple granulomatous foci, which manifest as multiple pulmonary nodules. Multiple pulmonary nodules are not always malignant, and it is recommended that patients seek medical attention as soon as possible to identify the cause of the disease and treat it in a timely manner.