Advanced stage of lung cancer includes locally advanced stage IIIA, stage IIIB and stage IV. Initial chemotherapy includes neoadjuvant and adjuvant chemotherapy for 4 times and stage IV chemotherapy for 6 times. If chemotherapy fails and is replaced by another chemotherapy agent, another 6 times of chemotherapy can be given again. In order to prolong the survival of patients, pemetrexed is used in clinical practice as a maintenance treatment for non-squamous non-small cell lung cancer, and the number of chemotherapy treatments is used until the lung cancer progresses. The effects of the above chemotherapy are mainly to kill the primary and metastatic tumor cells, shrink the tumor lesions, increase the tumor resection rate, and improve the survival rate and quality of life of patients.