Abstract: The worldwide outbreak of a novel coronavirus (COVID-19) in December 2019 significantly affected the routine diagnosis and treatment of breast cancer due to resource and staffing constraints. In addition, breast cancer patients have poor immunity and are, therefore, more susceptible to COVID-19. If they are infected, the risk of severe illness is extremely high. Therefore, finding a balance between the effective prevention and control of COVID-19 and diagnosing and treating patients with breast cancer is a significant clinical issue during the pandemic. Therefore, the National Cancer Quality Control Center Breast Cancer Expert Committee brought together experts to urgently compile a "Guideline for the Rationalized Diagnosis and Treatment of Breast Cancer during the Outbreak of Corona Virus Disease 2019". Here, we will interpret the core recommendations in the guideline for breast cancer diagnosis and treatment.