The concept of sentinel lymph node (SLN) was first introduced in 1977 by Cabanas RM in his study of penile tumors. The lymphography revealed that penile tumors drained to a specific group of lymph nodes that were clinically anatomically and pathologically proven to be the first site of metastasis and were named SLN. Sentinel lymph node biopsy technique （The core idea behind the use of sentinel lymph node biopsy (SLNB) in breast surgery is to find evidence to avoid axillary dissection by evaluating the metastatic status of the axillary lymph nodes in breast cancer, thus minimizing trauma. It is believed that SLNB can provide the same clinical information about the axilla as axillary lymph node dissection (ALND), and it significantly increases the detection rate of positive axillary lymph nodes in patients with stage T1 and T2 breast cancer. SLNB is currently used in breast cancer cases with a tumor diameter of less than 5 cm and negative axillary lymph nodes on clinical palpation. The main contraindications are pregnancy or lactation, previous surgical treatment of the affected breast or axilla, and the appropriateness of SLNB for multicentric cancer and after neoadjuvant chemotherapy is still controversial. Depending on the tracer, there are three main methods of SLNB: (1) dye method: methylene blue and other tracers; (2) nucleotide method: 99mTc-labeled sulfur colloid and antimony colloid as tracers; (3) combination method: combining blue dye and nucleotide as tracers. The American Society of Clinical Oncology (ASCO) guidelines for the clinical management of breast cancer have recommended SLNB technique as the initial axillary treatment for clinical stage I and II breast cancer cases with negative axillary lymph nodes, and the decision to perform ALND is based on the results of SLNB. the NCCN 2008 guidelines for the treatment of breast cancer similarly recommend that clinical stage I and II breast cancer cases with indications for SLNB should be treated with SLNB when the treatment The US randomized clinical trial NSABP B-32 randomized 5611 women with invasive breast cancer into an ALND after SLNB group (n=2807) and an ALND without SLN group (n=2804) with negative intraoperative cytology or pathology. ALND group (n=2804), comparing the clinical outcomes of SLNB alone and SLNB+ALND, suggesting that the success rate of SLNB was 97.2%, accuracy was 97.1%, false negative rate was 9.8%, dye related allergy rate was 0.7%, and different sites of tumor, different biopsy methods and the number of SLN detected were significant factors affecting the false negative rate . The ALMANAC clinical trial in the UK randomized 1031 breast cancer patients into SLNB group (n=515) and ALND group (n=516), and the preliminary results showed that the success rate of SLNB was 96.1%, the accuracy was 97.6%, and the false-negative rate was 6.7%, and SLNB using the combined method could improve the success rate and accuracy. In 2006, sentinel lymph node biopsy was included in the NCCN clinical practice guidelines for breast cancer; in 2009, the guidelines recommended that SLNB is the preferred method for axillary lymph node staging when local conditions are suitable for lymph node biopsy in I and II breast cancers, if an experienced SLNB team is available; in 2011, the Chinese version of the NCCN guidelines, also recommended the clinical application of SLNB .