Objective: To analyze the learning curve of sentinel lymph node biopsy in early-stage invasive breast cancer. Methods: Sixty patients with early-stage invasive breast cancer undergoing modified radical mastectomy between March 2011 and October 2012 were enrolled. The patients were divided into group A, B and C according to the time order of operation, with 20 cases in each group. The patients underwent sentinel lymph node biopsy before modified radical mastectomy. The operative time, success rate, false negative rate and sensitivity of sentinel lymph node biopsy among groups were compared. Results: The operative time in group A, B and C was (36.6±8.2), (25.1±7.4) and (17.3±5.6) min respectively, and there was statistical difference among the three groups (P<0.05). The success rate, false negative rate, and sensitivity of sentinel lymph node biopsy in group A was 65.0%, 55.6% and 44.4%, in group B was 95.0%, 11.1% and 88.9%, and in group C was 100.0%, 0 and 100.0% respectively, and all the differences in these parameters were statistically different (all P<0.05). Conclusion: With the completion of 20 performances of standardized sentinel lymph node biopsy, one can basically grasp this technique, and may reach full mastery after 40 performances.