Objective To explore the clinical value of methylene blue in sentinel lymph node biopsy ( SLNB) in breast conservative therapy of breast cancer. Methods 55 patients performed sentinel lymph node biopsy( SLNB)in were analyzed,with breast conservative therapy of breast cancer in clinical stage Ⅰ-Ⅱ. The mapping procedures and SLNB were performed using subareolar injection of Methylene blue dye,followed by the axillary lymph node dissection(ALND). All of the SLN and ALN were evaluated pathologically after the operations. Results Among 55 cases ,52 cases were checked out sentinel lymph node and the positive rate was 95% (52/55). The axillary status was 100% accurately predicted by SLNs;Sensitivity in this group was 93% (52/55) ;False negative rate was 5% (1/20);False positive rate was 0. Conclusion Methylene blue dye is a reliable method for sentinel lymph node biopsy. SLNB is a simple and safe technic, which helps to reveal the state of the axillary lymph nodes.