The lung is rich in blood vessels and is the most metastatic organ for malignant tumors. Tumors from all tissues and organs of the body can basically metastasize to the lung. The most common primary tumor sites where lung metastasis occurs are female reproductive system, digestive system and respiratory system respectively. Among the clinical cases of lung metastasis, 80%-90% are multiple and 10%-20% are confined or isolated. Metastases occur in most cases within 2 years after the appearance of the primary carcinoma, and in fewer cases after 3 years, although there are cases in which metastases occur after up to 10 years. In a few cases, lung metastases are detected earlier than the primary tumor. With the development of individualized comprehensive treatment for lung cancer and the prolongation of survival of tumor patients, the incidence of metastatic lung tumors is increasing. It is generally believed that the biological characteristics of the primary cancer and the immune status of the body are the most important factors for the occurrence of lung metastatic tumors. Therefore, in today’s high incidence of tumors, it is recommended to routinely perform chest CT test before treatment and during post-treatment follow-up to understand the accurate staging before treatment and early detection of lung metastases. Early lung metastases mostly have no obvious symptoms and are often detected during the regular review of the primary cancer. The severity of symptoms is closely related to the tissue type of the primary tumor, the metastatic route and the extent of involvement. Most cases have symptoms of the primary cancer. Early stage lung metastases mostly have no obvious respiratory symptoms. If the lung lesions are extensive, dry cough, sputum and blood and dyspnea may appear. If complicated with cancerous lymphangitis, massive pleural effusion, pulmonary atelectasis or superior vena cava compression, the dyspnea will be more obvious. Fever may occur secondary to infection. The most common X-ray manifestation of metastatic lung tumor is isolated or multiple nodular lesions in the lower and middle lung fields. As the lesions increase in size and number, they may fuse with each other to form giant masses. Choriocarcinoma often appears as a spherical foci of cotton balls. Metastatic lung cancer from the gastrointestinal tract may show diffuse corn-like or reticulated shadows. Metastatic squamous carcinoma, occasionally, may form atypical cancerous cavities. A few slower-growing metastatic breast cancers may form diffuse pulmonary fibrosis. Pleural effusion due to metastatic carcinoma in women is mostly from advanced breast cancer. In general, the main distinguishing points between metastatic lung cancer and other diseases are: rapid changes, with tumor enlargement and increase visible in a short period of time. Some of them are after resection of the primary tumor or after radiotherapy, chemotherapy. Sometimes it can shrink or disappear. It is sometimes difficult to distinguish primary tumor of lung from secondary tumor. In clinical practice, isolated lesions appear again in the lung after resection of primary lung cancer, which may be either multiple primary cancers or lung metastases at different times. If the cells of the second primary cancer are of the same pathological type as those of the first primary cancer, its differentiation is even more difficult. Treatment 1. Surgery Lung metastases belong to the category of advanced tumors. Surgical intervention should be considered as a palliative adjunct in comprehensive treatment, whose greatest significance is to most effectively reduce the tumor load or relieve the various symptoms caused by metastatic lesions to achieve the purpose of reduction or reduction of symptoms. The surgical approach to lung metastases is still based on the principle of maximizing the preservation of healthy lungs. The nature of surgery is palliative surgery, so local excision is appropriate. Chemotherapy is an indispensable tool for lung metastases. The specific chemotherapy program mainly adopts different chemotherapy drugs with different mechanisms according to different primary tumors. 3.Radiotherapy Radiation therapy can also be applied to tumors that are sensitive to radiation, especially if the metastases are single and the patient’s condition is not suitable for surgery. 4.Prognosis The prognosis of lung metastases is affected by many factors, such as the nature of the primary tumor, the number and size of metastases, the presence of other involved organs, and also the corresponding adjuvant therapy. After years of efforts, we have accumulated rich experience in the early diagnosis and individualized comprehensive treatment of lung cancer. We are currently at the leading level in China and strive to keep pace with the frontier of international development. In order to further expand the scope of the discipline and seize the opportunity of transformation and development, we have made active and fruitful exploration in the diagnosis and treatment of systemic tumors. Currently, in the subdirection of the discipline, we are working on the comprehensive diagnosis and treatment of pulmonary metastatic tumors, and have made certain achievements, especially in the diagnosis and treatment of pulmonary metastases of gynecologic malignancies, and have accumulated certain experience.