Abstract: Breast cancer is the most common malignancy in women in most of countries. During the past decades, the application of PET with ¹⁸F-fluoro-2-deoxy-D-glocuse (¹⁸F-FDG) has remarkably improved the managemant of breast cancer. Nevertheless, due to anatomical localisation of ¹⁸F-FDG uptake was difficult, the clinical interpretation of ¹⁸F-FDG PET scan could not be exactly. A novel combined PET-CT system has largely improved the capacity of sensitivity and specificity in the diagnosis of breast cancer. In this artiacal we focus on the application value of PET-CT to breast cancer diagnosis, with respect to dissease re-staging, treatment monitoring, preoperative staging and radiotherapy planning.