In this study, radiation therapy was performed on mouse breast cancer spontaneous gene mice (MMTV-PyMT) to obtain radiation therapy model of breast cancer mice. To simulate clinical breast cancer radiotherapy and study the differential proteins of breast cancer radiotherapy resistance. MMTV-PyMT mice were randomly divided into two groups, and the radiotherapy group was given the same dose 5 times (3GY, once every 2 days) when the breast cancer tumor grew to an appropriate size (200mm3). The protein extracted from mouse tumor was analyzed by mass spectrometry.