Abstract: Objective To investigate the clinical effect of dissection of axillary lymph nodes with ultrasonic scalpel in modified radical mastectomy for breast cancer. Methods A total of 110 patients undergoing modified radical mastectomy for breast cancer were selected as study objects, and were divided into two groups by random number table method, with 55 cases per group. General electric scalpel and ultrasonic scalpel were respectively given to the control group and the observation group for modified radical mastectomy. The clinical indexes(time of surgery, amount of bleeding during the surgery, indwelling time of axillary drainage tube, the number of lymph nodes cleaned)and the occurrence of postoperative complications were compared. Results The operative time, the amount of bleeding during surgery and indwelling time of axillary drainage tube of the observation group were better than those in the control group, while the number of lymph nodes cleaned was more than that in the control group, and the differences were statistically significant(P<0.05). The incidence of postoperative complications was 3.64%(2/55)in the observation group, which was significantly lower than 18.18%(11/55)in the control group(P<0.05). Conclusion In modified radical mastectomy of breast cancer, ultrasonic scalpel in axillary lymph node dissection has better clinical efficacy, and lower incidence of adverse reactions.