Objective To investigate the effect of radiotherapy for primary lesions and regional metastatic lymph nodes after chemotherapy on the outcome of patients with metastatic triple-negative breast cancer（TNBC）. Methods A retrospective analysis was performed on the whole clinical data of 50 patients with metastatic TNBC who were admitted to our hospital from May 2012 to December 2015. Among them，25 patients in the control group received systemic chemotherapy alone and the other 25 patients in the observation group received intensity-modulat⁃ed radiation therapy for the primary lesions and regional metastatic lymph nodes after systemic chemotherapy，with gross tumor volume of 6000 cGy/25 f/5 w，gross tumor volume of nodes of 6000 cGy/25 f/5 w，planning tumor volume of 5000 cGy/25 f/5 w，and local electron-beam boost irradiation of 1000-1600 cGy/5-8 f. A comparative analysis was performed on the outcomes and adverse reactions of patients. Results There was no significant difference in the efficacy of chemotherapy between the observation group and the control group（P>0.05）. The primary lesions had a complete response（CR）rate of 48%，a partial response（PR）rate of 52%，and an overall response rate（ORR）of 100%，and the regional metastatic lymph nodes had CR，PR，and OR rates of 56%，44%，and 100%，respectively. The observation group and control group had median locoregional failure-free survival time of 16 months（8 to 40 months）and 11 months（4 to 20 months），respectively，with a significant difference between the two groups（P=0.003）. The observation group and control group had median overall survival time of 17 months（8 to 48 months）and 13 months（6 to 26 months），respectively，with a significant difference between the two groups（P=0.019）. No serious toxicity and side effects were found. Conclusion Radiotherapy after chemotherapy can improve the progno⁃sis of patients with metastatic TNBC.