Objective To explore the clinical efficacy of Guishao Shengbai decoction on bone marrow suppression in patients undergoing chemotherapy after breast cancer surgery. Methods 106 patients undergoing chemotherapy after breast cancer surgery in the hospital were selected between January 2018 and December 2020, and they were randomly divided into control group and observation group with 53 cases in each group. The control group was treated with CEF chemotherapy, and the observation group was given Guishao Shengbai decoction during chemotherapy. The clinical efficacy, scores of TCM syndromes, bone marrow suppression degree and quality of life score were observed after a chemotherapy cycle （21 d）, and the drug safety was evaluated. Results After chemotherapy, the scores of TCM syndromes were decreased in observation group （P<0.05） while the scores were increased in control group （P<0.05）. After chemotherapy, the scores of various TCM syndromes in observation group were significantly lower than those in control group（P<0.05）. Compared with before chemotherapy, the levels of peripheral blood WBC, Hb and PLT were reduced at each time point after chemotherapy in the two groups （P<0.05）, and the above indicators in observation group at each time point after chemotherapy were significantly higher than those in control group （P<0.05） After chemotherapy, the incidence rate of bone marrow suppression≥ grade III of 9.43% in observation group was significantly lower than 24.53% in control group（P<0.05）. The KPS scores in the two groups were lowered after chemotherapy（P<0.05）, but the KPS score was higher in observation group than that in control group after chemotherapy（P<0.05）. During chemotherapy, the incidence rates of nausea and vomiting, diarrhea and constipation in observation group were significantly lower than those in control group（P<0.05）, and there was no statistically significant difference in abnormal rate of liver-kidney function between the two groups（P>0.05）. Conclusion Guishao Shengbai decoction can effectively inhibit the bone marrow suppression in patients undergoing chemotherapy after breast cancer surgery, and it has high safety and is worthy of clinical promotion.