There is no such thing as the most severe breast cancer in clinical practice, the severity of breast cancer is related to the stage, but Her2 positive breast cancer is known as the most aggressive breast cancer because this type of cancer grows faster and is more invasive compared to ordinary breast cancer. Her2-positive breast cancer stimulates the cancer cells to grow, divide, and metastasize wildly, a characteristic that makes the disease more likely to recur after treatment. Current treatments for Her2-positive patients include surgical treatment, chemotherapy, radiotherapy and targeted therapy, which can reduce the risk of death and improve the survival rate of patients. It is important to note that breast cancer patients can minimize the adverse effects of the disease through “early detection, early treatment and early diagnosis”. If a patient has been diagnosed with breast cancer, he or she should cooperate with the doctor and take active treatment to avoid delaying the disease.