Abstract: OBJECTIVE To observe the clinical efficacy of boost marrow and fortify spleen decoction in preventing and treating myelosuppression of rectal cancer patients with neoadjuvant concurrent chemoradiation. METHODS 60 rectal cancer patients with myelosuppression induced by neoadjuvant concurrent chemoradiation from October 2015 to October 2017，were divided into treatment group and control group randomly. All patients completed pelvic intensity-modulated radiation therapy (Prescription dose: 95% PTV = 50 Gy/25 times， five times per week， from Monday to Friday)， along with concurrent chemotherapy (Capecitabine tablets; 825 mg/m²， taken orally， twice a day， radiotherapy days)， a total of five weeks. The treatment group was treated with boost marrow and fortify spleen decoction. The session was from the beginning of chemoradiation (the starting point of the study) to the 30th day after radiotherapy (the end point of the study). The control group was treated with concurrent chemoradiation. The occurrence of myelosuppression， TCM syndromes， quality of life were observed. RESULTS The incidence of Grade Ⅲ-Ⅳ myelosuppression of the treatment group was obviously lower than that of the control group (P<0.05); The doses of recombinant human granulocyte colony stimulating factor (rhG - CSF) of the treatment group were significantly lower than those of the control group (P<0.01); The average hospitalization time of the treatment group was shorter than that of the control group (P<0.05). There were no adverse reactions occurring like Ⅳ urinary and dyspepsia in both of the two groups. Compared with the control group， the TCM syndrome integral of the treatment group decreased (P<0.05); At the end of the study， the stable rate of KPS score in treatment group was 83.33%， higher than that in control group (56.67%)， P<0.05. CONCLUSION Boost marrow and fortify spleen decoction can significantly reduce the incidence of myelosuppression in rectal cancer patients with neoadjuvant concurrent chemoradiation， improve the relevant TCM clinical symptoms after treatment， delay the downward trend of KPS score， as well as make patients' treatment tolerance and quality of life higher， which is worthy of further study.