Objective：To investigate the effect of Angelica sinensis polysaccharides on the balance of Th17/Treg cells and the expression of related inflammatory factor proteins in bone marrow of mice with aplastic anemia.Methods 50 male BALB/c mice were randomly divided into normal group,model group,cyclosporineA group,APS low and high dose groups.A mouse model of aplastic anemia was prepared by combining radiation irradiation with allogeneic lymphocyte infusion.After modeling,the mice were orally administered for 28 days.The general condition,weight changes,and spleen index of the mice were observed.Blood samples were taken to test the changes in basic hematological parameters of peripheral blood,and HE staining was used to evaluate the pathological changes in mouse bone marrow tissue;ELSIA method for detecting bone marrow TGF-β1.The expression levels of proteins such as IL-10,IL-17A,and IL-6;FCM detection of bone marrow Th17,Treg cell ratio,and Th17/Treg cell balance changes.Results Compared with the normal group,the model group mice showed clumsiness in activity,lethargy,pale eyelids,lips,and ears,and reduced food and water intake;Both body weight and spleen index significantly decreased;The peripheral blood red blood cell,white blood cell,platelet count,and hemoglobin concentration were significantly reduced;Disordered bone marrow tissue structure and significantly reduced proliferation of hematopoietic tissue;The expression of IL-17A and IL-6 proteins is significantly upregulated,and TGF-β1.The expression of IL-10 protein was significantly downregulated;The proportion of Th17 cells in bone marrow significantly increased,the proportion of Treg cells significantly decreased,and the ratio of Th17/Treg cells significantly increased(P<0.01).Compared with the model group,the general condition of the low and high dose APS groups improved,with an increase in food and water intake,a significant increase in body weight and spleen index,a significant increase in peripheral blood red blood cell,white blood cell,platelet count,and hemoglobin concentration(P<0.05),an improvement in bone marrow tissue structure,and an increase in hematopoietic tissue proliferation (P<0.05);The expression of IL-17A and IL-6 proteins is significantly downregulated,and TGF-β1. The expression of IL-10 protein was significantly upregulated(P<0.05 or P<0.01);The proportion of Th17 cells in bone marrow significantly decreased,the proportion of Treg cells significantly increased,and the ratio of Th17/Treg cells significantly decreased (P<0.01).Conclusion Angelica sinensis polysaccharides can improve bone marrow hematopoietic function in AA mice,and its mechanism may be achieved by regulating Th17/Treg cell balance.