Objective To investigate the timing of stereotactic radiosurgery(SRS)in lung adenocarcinoma with epidermal growth factor receptor(EGFR)mutation treated with tyrosine kinase inhibitor(TKI).Methods A total of 90 patients with EGFR-mutated lung adenocarcinoma patients with brain metastasis admitted to the Fifth Affiliated Hospital of Zhengzhou University from January 2018 to December 2020 were collected.All patients received TKI treatment and were divided into two treatment groups according to the timing of SRS treatment:those who received SRS immediately after the diagnosis of lung cancer brain metastasis were called early SRS group(n=52),and those who received TKI treatment and then SRS after the progression of brain metastasis were called deferred SRS group(n=38).Objective response rate(ORR),disease control rate(DCR),intracranial progression-free survival(iPFS)and overall survival(OS)were compared between the two groups.Multivariate COX regression model was used to analyze the prognosis.Results There was no significant difference in ORR(59.6％vs 50.0％,P=0.365)and DCR(76.9％vs 73.7％,P=0.724)between the two groups.The median OS and iPFS of the whole group were 31.5months and 12.5months,respectively.The OS of the early SRS group was signifi-cantly longer than that of the late SRS group(35.5months vs 27.0months,P=0.001).iPFS was also significantly better in the early SRS group than in the late SRS group(15.0months vs 11.5months,P=0.004).The median OS was longer in patients with no symptoms of brain metastases than in patients with symptoms of brain metastases(35.5months vs 27.Omonths,P=0.011).Multivariate COX regression analysis showed that early SRS treatment was a protective factor for OS and iPFS(HR＜1,P＜0.05),and Lung-mol GPA score of 3.5-4.0 was a protective factor for OS(HR＜1,P＜0.01).Conclusion For patients with advanced EGFR-mutated lung adenocarcinoma with brain metastases,early SRS treatment after diagnosis of brain metastases has better intracranial control effect and greater survival benefit.