The survival time of patients with brain metastasis of lung adenocarcinoma is about 3 months if they are not treated actively, and if they can be treated actively, the survival time of patients can reach 3 years and above. Once brain metastasis of lung adenocarcinoma occurs, it indicates that the cancer has reached the advanced stage. Patients may have dizziness, headache, vomiting, projectile vomiting, sudden epilepsy, fainting, hemiplegia, cerebral edema and so on. If not actively treated, the survival time is around 3 months; if actively treated, through chemotherapy, radiotherapy, targeted drug therapy, microwave ablation therapy, interventional therapy, Gamma Knife therapy and other comprehensive treatments, as long as the growth, development and proliferation of the tumor are controlled, the patient’s survival time can be up to 3 years or even longer. Patients with brain metastasis of lung adenocarcinoma should keep optimistic mentality, take positive treatment measures, strengthen nutrition and improve resistance which is helpful for prolonging survival.