Translymphatic metastasis is the most common form of breast cancer metastasis, and the most common site of lymphatic metastasis is the ipsilateral axillary lymph node. The status of axillary lymph nodes is the most important indicator for determining the prognosis of breast cancer and guiding adjuvant therapy. For more than a century, axillary lymph node dissection has been an essential part of the surgical treatment of invasive breast cancer and has played a very important role in determining the disease and prognosis as well as in the selection of postoperative adjuvant therapy. However, axillary lymph node dissection can bring about many immediate and long-term complications, such as upper extremity edema, pain, impaired shoulder mobility, and numbness. In recent years, the advent of sentinel lymph node biopsy has led to a renewed understanding of the management of axillary lymph nodes. Sentinel lymph node biopsy is a surgical procedure that can predict the status of regional lymph nodes while reducing postoperative complications, and has become a landmark advance in breast surgery in the last decade. Here is a brief introduction of what is sentinel lymph node: Sentinel lymph node is a special lymph node among the regional lymph nodes draining from the primary tumor, and it is the first lymph node through which the primary tumor must pass for lymph node metastasis to occur. The clinical significance of sentinel lymph nodes as a barrier to prevent the spread of tumor cells from lymphatic tracts has received much attention. The clinical application of sentinel lymph node biopsy allows breast cancer patients without axillary lymph node metastasis to avoid axillary lymph node dissection, thus avoiding the corresponding surgical complications such as upper limb lymphedema and greatly improving the quality of life of patients, and therefore has received much attention. The first lymph node that is traced is accurately excised and biopsied. If the pathology is positive, axillary lymph node dissection is performed; if it is negative, axillary lymph node dissection is not necessary.