ObjectivesTo observe the clinical effectiveness， safety， and potential mechanism of Yisui Shengxue Pills （益髓生血丸） as adjuvant treatment for myelosuppression after chemotherapy for malignant tumours with qi and yin deficiency syndrome. MethodsEighty patients of myelosuppression after chemotherapy for malignant tumours with qi and yin deficiency syndrome were randomly divided into trial group and control group， with 40 cases in each group. Both groups received conventional western medicine treatment， while the control group added placebo taken orally， and the trial group received Yisui Shengxue Pills orally， and both groups were treated for 21 consecutive days. Granulocyte colony stimulating factor （G-CSF）， granulocyte-macrophage colony stimulating factor （GM-CSF）， soluble intercellular cell adhesion molecule-1 （sICAM-1）， Jagged 1 （Jagl）， Notch homolog 2 （Notch2）， cell fate determinant membrane associated protein 1 （Numb1）， neutrophils， platelet count， white blood cell count， hemoglobin， cluster of differentiation 4⁺ （CD4⁺）， and cluster of differentiation 8⁺ （CD8⁺） were detected before and after treatment； myelosuppression grade and TCM syndrome scores of the two groups were evaluated before and after treatment， and clinical effectiveness and adverse events of the two groups were compared. ResultsThe difference in myelosuppression grading between the two groups after treatment was statistically significant （P＜0.05）. Compared with this group before treatment， plasma G-CSF， GM-CSF， sICAM-1， Numb1 expression， platelet count， neutrophil count， leukocyte count， haemoglobin， CD4⁺ level decreased， Jagl， Notch2 expression and CD8⁺ level increased， and fatigue， spontaneous sweating， palpitation， night sweating， insomnia， scanty complexion， mouth erosion， vexing heat in chest， palms and soles scores all reduced （P＜0.05）. Compared with the control group after treatment， plasma G-CSF， GM-CSF， sICAM-1， Numb1 expression， platelet count， neutrophil count， leukocyte count， haemoglobin， CD4+ levels increased， Jagl， Notch2 expression and CD8⁺ levels decreased， and fatigue， spontaneous sweating， palpitations， night sweating， insomnia， pale face， mouth erosion， and vexing heat in chest， palms and soles scores decreased in trial group （P＜0.05）. The total effective rate of the trial group was 95.00%， which was significantly higher than that of the control group， which was 80.00% （P＜0.05）. Comparison of the incidence of liver function damage and renal function damage between the two groups showed no statistically significant difference （P＞0.05）， and the incidence of gastrointestinal damage in the trial group was lower than that in the control group （P = 0.02）. ConclusionYisui Shengxue Pills as adjuvant treatment for myelosuppression after chemotherapy for malignant tumours with qi and yin deficiency syndrome can improve the myelosuppression and clinical symptoms， improve the clinical effectiveness， and has a good synergistic and toxicity-reducing effect， and its mechanism of action may be related to the regulation of the Notch signalling pathway and the reduction of immune function impairment.