Targeted drugs can be used after brain metastasis from lung cancer, especially when lung adenocarcinoma is combined with EGFR gene mutation or ALK gene mutation. Targeted drugs, such as the first-generation gefitinib, erlotinib, erlotinib and third-generation oxitinib, have shown significant efficacy in brain metastases from lung cancer and were all included in a portion of the treatment of brain metastases from lung cancer at the time of clinical studies. The results showed that patients with lung adenocarcinoma already combined with brain metastasis could also cross the blood-brain barrier using targeted drugs, thus achieving tumor growth control, while no targeted drugs could be applied to small cell lung cancer brain metastasis. Therefore, whether targeted drugs can be used for lung cancer brain metastasis depends on the pathological type of lung cancer and whether it is combined with genetic mutations.