Objective To assess the clinical application value of axillary lymph node staging of breast cancer by B ultrasound.Methods From February to December 2014, 200 female breast disease patients in Department of Breast Surgery Affiliated Hospital of Academy of Military Medical Sciences, were enrolled, with median age 50 years old, including 153 cases of breast cancer, 44 cases of fibroadenoma, 2 cases of mastitis and a case of huge fibroma.The state of axillary lymph node was assessed by doctor with more than twenty years experience in B ultrasound diagnosis.According to the characteristics of the ultrasound image of lymph node and experience of the B ultrasound doctor, the patients were divided into axillary lymph node metastasis group, suspicious group and no metastasis group.The axillary lymph nodes were staged by sentinel lymph node biopsy or axillary lymph node dissection.Based on pathological diagnosis and results of the ultrasound, the sensitivity, specificity, positive predictive value, negative predictive value, false negative rate, and metastasis burden of axillary lymph nodes in false negative patients were analyzed.The relationship between the B ultrasound characteristics and axillary lymph node metastasis was also studied by univariate analysis.Results The metastasis rate of above-mentioned 3 groups by B ultrasound was 84.51%, 45.16% and 7.14%, respectively.The sensitivity, specificity, positive predictive value and negative predictive value of screening for axillary lymph node metastasis by B ultrasound were 89.6%, 89.1%, 84.5% and 92.7%, respectively in metastasis group and no metastasis group. According to consistency analysis between pathological diagnosis and B ultrasound, the Kappa value was 0.779.The false negative rate was only 7.1%(7/98 cases) in no metastasis group judged by B ultrasound, and the patients′axillary lymph node metastasis burden was very low, with only one lymph node positive.The univariate analysis showed that patients with longitudinal diameter of lymph nodes≥1 cm had a higher risk for metastasis than <1 cm (44.2%/14.3%,P<0.001);lymph node aspect ratio≤1.5, the lymph node metastasis rate was significant higher than>1.5(P<0.001); cortical thickness≥3 mm and lymph node appearing blood flow signal of the central or mixed type were also high metastasis risk factor, the lymph node metastasis rate was 67.5%, 75%and 79%, respectively, P<0.001).Conclusion B Ultrasound is a valuable method for detecting axillary lymph node metastasis in breast cancer.It has lower false negative rate, and the false negative patients just have smaller axillary lymph node metastasis burden.The longitudinal diameter of lymph nodes more than 1 cm, lymph node aspect ratio≤1.5, lymph node of cortical thickness≥3 mm, and blood flow signal of the central or mixed type have higher relationship with axillary lymph node metastasis.B Ultrasound may be a potential alterative method for sentinel axillary lymph node biopsy for axillary lymph node staging in early breast cancer.