To investigate the outcomes of SIB-WBRT in patients with brain metastases and analyze the impact of some factors on prognosis. This single-arm retrospective study analyzed patients with brain metastases who were treated with SIB-WBRT at Peking Union Medical College Hospital from September 2015 to December 2021. The primary endpoint was intracranial progression free survival (iPFS). Secondary endpoints included overall survival (OS), intracranial new foci, and tumor control. The Kaplan-Meier method was then used to depict and estimate iPFS, OS, intracranial neoplasia, and tumor control. Finally, the Cox model was used to analyze the association between some relevant factors and outcomes. A total of 107 patients were included and the median iPFS in these patients treated with SIB-WBRT was 13.4 (95% CI: 4.2-22.6) months, with 68.0% (95% CI: 57.4%-78.6%) and 50.8% (95% CI: 38.3%-63.3%) iPFS at 6- and 12-months. The median local control was 37.6 (95% CI: 28.3-46.8) months, with local control rates of 84.3% (95% CI: 80.6%-88.0%) and 73.3% (95% CI: 68.2%-78.4%) at 6- and 12-months. The median time to appearance of new intracranial foci was 17.4 (95% CI: 14.1-20.8) months, and the 6- and 12-month control rates were 74.5% (95% CI: 64.5%-84.5%) and 61.5% (95% CI: 49.0%-74.0%). The number of brain metastases in patients before treatment was significantly associated with iPFS (HR=0.4, 95% CI: 0.2-0.973, =0.043). The iPFS, local control, and intracranial new foci of patients with brain metastases after treatment with SIB-WBRT were acceptable. In addition, the number of brain metastases in patients before treatment may be associated with iPFS.