Neoadjuvant chemotherapy, also known as preoperative chemotherapy, was often chosen to be given postoperatively in the past. Why do we choose preoperative chemotherapy for some patients? The benefits of neoadjuvant chemotherapy: (1) By observing the change of tumor size before and after chemotherapy, the sensitivity of patients to the selected chemotherapy drugs can be evaluated preoperatively, avoiding the disadvantage that postoperative chemotherapy cannot evaluate the effect of chemotherapy. (2)t can improve the breast conservation rate of early breast cancer or the resectable rate of advanced breast cancer after tumor shrinkage through chemotherapy. (3) Patients who have achieved pathological complete remission after chemotherapy can improve the 5-year and 10-year survival rates. Scope of application: (1) Stage T0-Ⅱa, those with unremarkable axillary lymph node enlargement by clinical and ultrasound and X-ray examination or those who have undergone mass resection in external hospitals, can not be treated with preoperative chemotherapy. (2) Stage IIb-III operable breast cancer: 2-6 cycles of preoperative chemotherapy are performed according to the patient’s condition in order to understand the sensitivity of the tumor to the chemotherapy regimen and to achieve remission of the tumor lesion before considering surgery. (3) Locally advanced breast cancer and inflammatory breast cancer without obvious signs of systemic metastasis should be treated with preoperative chemotherapy, and the chemotherapy cycle can be extended appropriately according to the situation until the operable condition is reached. (4) Preoperative chemotherapy should be administered to those who have a strong demand for breast preservation, but the conditions for breast preservation are slightly inadequate, and the conditions for breast preservation are possible after preoperative chemotherapy. (5) For stage IV breast cancer, systemic treatment is the main treatment, and local tumor reduction surgery is feasible after the disease is controlled. (6) In principle, preoperative chemotherapy is not available for breast cancer over 70 years old. If the tumor is late and surgical resection is difficult, the patient can choose the appropriate preoperative chemotherapy regimen according to her physical condition, and anthracycline chemotherapy regimen should be used with caution.