Lung solid nodule refers to the substantial high-density shadow seen on chest CT, and the possible causes are chronic lung inflammation, tuberculosis, lung tumors, etc. 1. Chronic lung inflammation: chronic inflammation will stimulate the lungs to appear inflammatory nodules, often accompanied by long-term coughing, coughing up sputum, shortness of breath and other symptoms, the regular anti-inflammatory treatment for 2 weeks can be seen obvious nodule shrinkage. 2. Tuberculosis: primary tuberculosis is often seen in the lower part of the upper lobe or the upper part of the lower lobe near the subpleural lung tissue, accompanied by weakness, low fever, night sweats and other symptoms. 3. Lung tumor: according to the size of the nodule and the accompanying symptoms to determine the benign or malignant nature of the tumor, asymptomatic solid nodules less than 8mm can be chosen for regular observation, if accompanied by chest pain, hemoptysis, cough and other symptoms, or the nodule is large, the benign or malignant nature of the nodule needs to be clarified according to the specific circumstances to determine the further treatment plan. For solid lung nodules, it is recommended to go to a regular hospital as soon as possible for comprehensive evaluation by a thoracic surgeon to give further treatment plan.