Objective: To investigate the effect of trastuzumab combined with elemene injection on the expression of BNP and cTnⅠ in serum of breast cancer. Methods: 78 breast cancer patients treated in our hospital from February 2018 to June 2021 were divided into observation group (n=39) and control group (n=39) according to different treatment drugs. The observation group was treated with trastuzumab combined with elemene injection, and the control group was treated with trastuzumab injection only. The therapeutic effect, preoperative and postoperative T-lymphocyte subsets, quality of life, toxic reactions, serum BNP and cTnⅠ levels were compared between the two groups. Results: (1) The total effective rate of observation group was higher than that of control group (P<0.05). (2) The total incidence of toxicity in observation group was 15.38 %, significantly lower than 35.90 % in control group (P<0.05). (3) After treatment, CD3+ and CD4+ levels in the observation group were higher than those in the control group (P<0.05), while CD8+ levels were lower than those in the control group (P<0.05). (4) After treatment, the serum BNP and cTnⅠ levels increased gradually with the prolongation of treatment cycle, and the serum BNP and cTnⅠ levels in control group were increased compared with observation group in the same cycle (P<0.05). (5) After treatment, the scores of physical function, cognitive function and overall health status in observation group were higher than those in control group(P<0.05). Conclusion: The feasibility of trastuzumab combined with elemene injection in the treatment of breast cancer is good, which can significantly improve the treatment efficiency, improve the quality of life and immune function of patients, and reduce the serum BNP and cTnⅠ levels, which is worthy of clinical application. [ABSTRACT FROM AUTHOR]