〔Abstract〕 Objective To study the application of Yangzheng mixture in the treatment of patients with spleen and stomach weakness complicated by postoperative chemotherapy for breast invasive ductal carcinoma. Methods A total of 82 patients with postoperative chemotherapy for invasive ductal carcinoma of breast complicated with dystrophy of spleen and stomach weakness were selected from the Second Affiliated Hospital of Shaanxi University of Chinese Medicine from December 2019 to January 2021. These patients were randomly divided into an observation group and a control group, with 41 patients in each group. Patients in the control group received routine treatment, and patients in the observation group were treated with Yangzheng mixture on the basis of the treatment of patients in the control group. After treatment, the taditional Chinese medicine (TCM) syndrome efficacy (TCM symptom score) of patients in the two groups was compared. Nutritional status [serum albumin (ALB), apolipoprotein B100 (ApoB100), transferrin (TRF)] and immune function [T helper cells (CD4⁺ ), T killer cells (CD8⁺ )] were compared between the two groups before and after treatment, and tumor recurrence rate was compared between the two groups 6 months after treatment. Results After treatment, the symptom score and CD8⁺ ratio in the two groups were decreased, and the indexes in the observation group were significantly lower than those in the control group, the differences were statistically significant (P < 0.05). The levels of serum ALB, ApoB100, TRF levels and CD4⁺ ratio in the two groups were significantly increased, and the levels in the observation group were significantly higher than those in the control group, the differences were statistically significant (P < 0.05). Six months after treatment, the recurrence rate of tumor in the observation group was 9.76 % (4/41) lower than that in the control group 14.63 % (6/41), with no statistical significance (P > 0.05). Conclusion Yangzheng mixture can effectively improve the nutritional status of patients with the syndrome of spleen and stomach weakness complicated by postoperative chemotherapy for breast invasive ductal carcinoma, and has positive significance for relieving the symptoms of patients and improving the body's immune function.