Purpose To explore the diagnostic value of shear wave elastography in radiation brachial plexus neuropathy in patients with breast cancer, and to analyze the correlation between follow-up time after radiotherapy,brachial plexus radiation volume, radiation dose and brachial plexus elastic modulus and shear wave velocity. Methods According to the LENT-SOMA scale, 84 patients with breast cancer were divided into group A (grade 1，n=45),group B (grade 2，n=34) and group C (grade 3，n=5), and 40 healthy women in the same period were selected as control group. The differences of thickness,perimeter and cross-sectional area of brachial plexus among groups were compared.The elastic modulus and shear wave velocity of brachial plexus weremeasured by SWE technique, and the ROC curve was drawn.The follow-up time after radiotherapy, brachial plexus radiation volume and radiation dose of breast cancer patients were recorded. Results There was no significant difference in the thickness of brachial plexus among the four groups,so were the difference in the perimeter and cross-sectional are between group A and control group, group B and group C(P＞0.05),but the perimeter and cross-sectional area of brachial plexus in group B and group C were significantly higher than those in group A and control group (P＜0.05),the difference was statistically significant.There were significant differences in brachial plexus elastic modulus and SWV among different groups.The values ofelastic modulus and SWV of brachial plexus in group B and C were significantly higher than those in group A, and the values of elastic modulus and SWV in group C were significantly higher than those in group B (P＜0.05). The results of correlation analysis showed that the follow-up time, brachial plexus radiation volume and dose in group A, B and C were positively correlated with brachial plexus elastic modulus (r = 0.333, 0.414, 0.465，P＜0.05) and SWV (r = 0.345, 0.421, 0.482 P＜0.05). Conclusion SWE technique can quantitatively evaluate the changes of brachial plexus elasticity and provideimaging reference for early detection and early diagnosis of RIBP.