Abstract: Objective To investigate the effect of mastoscopy assisted axillary lymph node dissection(ALND) surgery on upper limb function and quality of life of patients with breast cancer, and provide reference for treatment of breast cancer. Methods Total 172 cases early breast cancer in our department between June, 2010 and June, 2013 were enrolled and assigned into mastoscopic axillary lymph node dissection group(observational group) and conventional axillary lymph node dissection group(control group) with 86 cases in each group. The operation indicators, upper limb function and the quality of life were compared between the two groups. Results The amount of intraoperative bleeding and volume of axillary drainage in the observational group was significantly lower than that of the control group[(65.42±7.37 vs. 185.53±22.86)ml, (114.25±35.06 vs. 188.79±48.13)ml, respectively], t=46.375, 11.609, P<0.05; The 6-month follow-up showed that the angle of shoulder flexion, extension, adduction, abduction, pronation, and external rotation in the observational group were significantly greater than those in the control group(t=7.689, 5.339, 4.176, 16.805, 9.269 and 9.395, P<0.05); The incidence of complications such as limb paresthesia was 10.47% in the observational group, which was significantly lower than 40.70% in the control group (χ²=20.645, P<0.05). The scores of cognitive function, physical function and other quality of life in the observational group were significantly higher than those in the control group (t=5.998, 7.213, 6.439, 5.551, P<0.05). Conclusion Mastoscopy assisted axillary lymph node dissection is helpful to reduce the trauma, promote the recovery of upper limb function, improve the quality of life.