Abstract: Objective:To investigate the clinical value of the intraoperative molecular diagnosis of sentinel lymph node in breast cancer,and provide the accurate and convenient intraoperative diagnosis method for breast cancer.Methods:The sentinel lymph node biopsies in 73 patients during operation were examined.The molecular diagnosis,quick frozen pathological detection and printing slice cytology test in intraoperative sentinel lymph node tissue of breast cancer were detected.The pathology of the layered sentinel lymph node tissue block after surgery was finished,and the result of which was set as the diagnostic gold standard.Results:The diagnostic sensitivities of molecular diagnosis,quick frozen pathological detection and printing slice cytology in sentinel lymph nodes of breast cancer were 84.62%,73.08% and 69.23%,respectively,and the sensitivity of molecular diagnosis in sentinel lymph node of breast cancer was significantly higher than that of quick frozen pathological detection and printing slice cytology test(P<0.05).Among the 70 times of molecular diagnosis test in sentinel lymph node of breast cancer,the average operation time of the first 10 times,11 to 25 times and 26 to 70 times was(53.28±3.93)min,(42.19±3.44)min and (31.73±2.57)min,respectively.With the increasing of operating frequency and shortening of operation time,the good learning curve was found(P<0.01).The cycle thresholds of mammaglobin and cytokeratin 19 were significantly negatively correlated with the metastases size(P<0.05).Conclusions:The diagnostic sensitivity of molecular diagnosis in sentinel lymph node of breast cancer is higher than that of quick frozen pathological detection and printing slice cytology test.The molecular diagnostic method is easy to grasp,and has high clinical values.