Lung cancer can be divided into central lung cancer and peripheral lung cancer, and the specific manifestations are as follows: 1. If the mass is large and obstructs the bronchus, it can cause secondary changes, such as secondary obstructive pneumonia and obstructive atelectasis; 2. Peripheral type lung cancer: it mainly shows the formation of masses around the lung, and the characteristic signs are lobar sign and vacuolar sign, and fine burr sign, pleural depression sign and vascular cluster sign can often be seen around the mass. If the mass invades the pericardium, it can cause pericardial effusion. If the mass invades the pleura, it will cause pleural effusion. If distant metastasis occurs in the middle and late stage of the tumor, liver metastasis, adrenal metastasis, brain metastasis and systemic bone metastasis can be seen. In different patients, their manifestations are not exactly the same. The incidence of lung cancer has been on the rise in recent years, and lung cancer is one of the common malignant tumors. Therefore, early diagnosis and early treatment are the objectives to be achieved and the advantages of CT examination.