Objective  To explore whether astragaloside Ⅳ (AS-Ⅳ) can protect radiation-induced kidney injury through toll-like receptor 4（TLR4）/nuclear factor kappa B（NF-κB）-mediated signaling pathway.    Methods  The mice were randomly divided into normal control group, DMSO solvent group, irradiation group (IR), IR + AS-Ⅳ 20 mg/kg group and IR + AS-Ⅳ 40 mg/kg group. One month after intraperitoneal injection of AS-Ⅳ, the mice were irradiated with 8 Gy 60Coγ and to the content of serum creatinine (Cr) and uric acid (BUA) in serum were determined, HE and immunohistochemical staining, and expression of TLR4/NF-κB signaling pathway related protein in kidney were performed.    Results  Compared with the control group, the levels of Cr and BUA in the serum of the radiation group increased significantly (P<0.001), glomerular atrophy and tubular expansion, TLR4 and myeloid differentiation factor 88(MyD88) positive expression increased significantly (P<0.001), and the expression of TLR4/NF-κB signaling pathway-related proteins［TLR4, MyD88, NF-κB, interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α)］ increased significantly (P<0.01); AS-Ⅳ pretreatment can reduce the content of Cr and BUA in serum (P<0.05, P<0.01 or P<0.001), significantly improve the pathological response caused by radiation, and reduce the expression of TLR4/NF-κB signaling pathway-related proteins (P<0.05 or P<0.01).    Conclusion  AS-Ⅳ may down-regulate the release of inflammatory factors through the TLR4/NF-κB signaling pathway, thereby improving radiation-induced kidney injury in mice and playing a protective role.