Lung abscess and lung cancer are both common lesions in the lung, but there are obvious differences between them, and the specific differential diagnosis mainly includes clinical symptoms, imaging examination, blood test and puncture biopsy, etc. Lung cancer will have obvious chest pain, cough and hemoptysis. 1. Clinical symptoms: lung abscess is closely related to infection, which will lead to high fever, coughing and coughing up purulent sputum; lung cancer will have obvious symptoms of chest pain, coughing and hemoptysis, and will lead to obvious decline in health condition. 2. Imaging examination: in CT enhanced examination of lung abscess, the center of the lesion is liquid without obvious enhancement, and the surrounding wall is uniform and obvious enhancement, most of which is accompanied by inflammation in the lungs; lung cancer mainly manifests itself as a soft tissue mass, with uneven edges, and malignant signs such as burr, lobulation and pleural pulling can be seen. 3. Blood test: blood test of lung abscess mainly shows obvious increase of white blood cells and C-reactive protein; examination of lung cancer can find increase of tumor markers. 4. Puncture biopsy: try not to puncture lung abscess when it is suspected; malignant cells found by pathological puncture can diagnose lung cancer. If occupying lesions are found in the lungs, relevant examinations should be carried out first to confirm the cause of the disease and then standardized treatment should be carried out.