Objective To evaluate the efficacy and safety of intensity modulated radiation therapy (IMRT) for whole-brain radiotherapy with simultaneous integrated boost for brain metastases.Methods From January 2015 to January 2017,120 patients with brain metastases undergoing hospital radiotherapy at the First People's Hospital and the Second People's Hospital of Yulin City of Guangxi Zhuang Autonomous Region were randomly divided into three dimensional conformal radiation therapy (3DCRT) group (n =60) and IMRT group (n =60) by envelope method.The curative effects of the two groups and the changes of patient's mental states before and after radiotherapy were compared.Results The median survival times of patients in 3DCRT group was 11.5 months,and the 6 months and 1 year survival times rates were 83.3％ and 35.0％ respectively.The median survival times of patients in IMRT group was 12.9 months,and the 6 months and 1 year survival rates were 86.7％ and 38.3％ respectively.There was no significant difference in prognosis between the two groups (x2 =0.143,P =0.705).There were 8 cases with complete remission,38 cases with partial remission,11 cases with stable disease,3 cases with progressive disease in 3DCRT group,and there were 9,40,9,2 cases in IMRT group respectively.There was no statistically significant difference in short-term efficacy between the two groups (Z =-0.641,P =0.520).Univariate analysis results showed that recursive partitioning analysis (RPA) classification (x2=53.484,P ＜0.001),extracranial lesions control (x2=13.392,P ＜ 0.001),whether the midline offset (x2 =4.427,P =0.035) were prognostic factors.Multivariate analysis results showed that RPA classification (HR =2.631,95 ％ CI:1.884-3.673,P ＜ 0.001),extracranial lesions control (HR =1.697,95％ CI:1.034-2.786,P =0.037),whether the midline offset (HR =1.787,95％ CI:1.118-2.856,P =0.015) were the independent prognostic factors for the overall survival.According to the results of activities of mini-mental state examination,the scores of 3DCRT group before and after radiotherapy were 27.12 ± 2.42 and 26.08 ± 2.42 respectively,with a significant difference (t =2.723,P =0.009);and the scores of IMRT group before and after radiotherapy were 26.57 ± 3.09 and 27.20 ± 2.46 respectively,with no significant difference (t =-1.610,P =0.1 13).Conclusion IMRT for whole-brain radiotherapy with simultaneous integrated boost is an effective treatment for multiple brain metastases,which can relieve symptoms,prolong survival time and improve quality of life.