Primary lung cancer is the most common malignancy and the leading cause of cancer death in China, with an estimated 787 thousands incident cases and 631 thousands deaths in 2015. Due to its aggressive behavior and the absence of effective early screening methods, most patients with lung cancer in China are in stage Ⅳ when diagnosed . Chemotherapy is the cornerstone of advanced lung cancer, but its efficacy is unsatisfactory. In recent years, with the rapid development of molecular targeted therapy and immunotherapy, the treatment concept has continuously changed and survival for patients has also been greatly improved. In order to update the progress in the treatment of stage Ⅳ lung cancer worldwide timely, and further improve the level of standardized diagnosis and treatment of stage Ⅳ lung cancer in China, Chinese Association for Clinical Oncologists organized experts to formulate《Clinical Practice Guideline for Stage Ⅳ Primary Lung Cancer in China(2020 version)》.