Brain metastases are common in lung cancer patients, indicating a poor prognosis and short survival time. In recent years, with the development of surgery, radiotherapy and medical therapy, the survival time of lung cancer patients with brain metastases has been prolonged owing to more and more treatment options. In order to reflect the progress in the treatment worldwide timely, and further improve the level of standardized treatment of lung cancer with brain metastases in China, Chinese Association for Clinical Oncologists and Medical Oncology Branch of Chinese International Exchange and Promotion Association for Medical and Healthcare organized experts to formulate "Clinical practice guideline for brain metastases of lung cancer in China (2021 version)" .