Sentinel lymph node biopsy for breast cancer usually takes 2-5 nodes. Anatomically, sentinel lymph nodes are the first station lymph nodes that receive lymphatic fluid from a certain organ or tissue area; in general, sentinel lymph nodes are equivalent to the first station sentinels, which can determine whether breast cancer has metastasized or not; the average number of breast sentinel lymph nodes is 2~3, and 15% of the patients have 4 or more; if the sentinel lymph node pathology report doesn’t show metastasis, then it is probable that the breast cancer is in the early stage and hasn’t spread. If there is no metastasis in the sentinel lymph nodes, then the probability is that the breast cancer has not spread in the early stage. However, there is a case called jumping metastasis, which means that the sentinel lymph node has not metastasized but the next lymph node behind it has metastasized, but the probability of this case is low; therefore, we will decide whether or not to do axillary lymph node dissection according to the situation during the operation. Clinical breast cancer surgery axillary sentinel lymph node biopsy is done with dual tracers; for patients with small masses, strong desire for breast conservation, and willingness to cooperate with postoperative adjuvant therapy, sentinel lymph node biopsy is the appropriate test. It is recommended that the next step of treatment be taken in conjunction with the subsequent pathology report.