Objectives: To assess side effects on Cantharidin sodium and Shenmai injection combined with chemotherapy in treating patients with breast cancer postoperatively. Method: Patients with breast cancer receiving postoperative chemotherapy were retrospectively collected, and divided into four groups: group A with cantharidin sodium injection combined with chemotherapy; group B with Shenmai injection combined with chemotherapy; group C with both cantharidin sodium and Shenmai injection combined with chemotherapy; while group D (control group) received chemotherapy alone. All patients were administered docetaxel at a dose of $75mg/m^2$ on day 1, epirubicin hydrochloride at a dose of $60mg/m^2$ on day 1, and cyclophosphamide at a dose of $500mg/m^2$ on day 1 for 3 cycles (repeated at 21 day intervals). After ${geq}$ three courses of treatment, quality of life and side effects were evaluated. Results: There were a total of 78 patients in this study, and the incidence of leukopenia and gastrointestinal reactions in groups A and B were lower than those in the control group and lowest in group C (p<0.05). Conclusions: Thus cantharidin sodium and Shenmai injection combined with chemotherapy reduce side effects and deserve to be further investigated in randomized clinical control trials.