〔Abstract〕 Objective To investigate the effects of astragalus mongholicus extract(AME) on lung injury and the myeloid differentiation factor 88(MyD88)/Toll-like receptor 4(TLR4)/nuclear factor kappa B(NF-κB) p65 pathway in rheumatoid arthritis induced interstitial lung disease(RA-ILD) rats. Methods SD rats were randomly divided into a control group, RA-ILD group, low-dose AME group(5 g/L), high-dose AME group(10 g/L), and high-dose AME+lipopolysaccharide(LPS) group(10 g/L AME+1 mg/L TLR4 activator LPS). Except for the control group, rats in all other groups were injected with bovine type Ⅱ collagen, Freund's complete adjuvant, and bleomycin to establish the RA-ILD model. The arthritis index and lung tissue wet-dry weight ratio of rats were tested. ELISA was applied to detect the levels of inflammatory factors interleukin(IL)-1β, IL-6 and tumor necrosis factor-α(TNF-α) in bronchoalveolar lavage fluid. Hematoxylin eosin staining was used to observe pathological changes of rat knee joint tissue and lung tissue. Western blot was applied to detect the expression of autophagy factors Beclin 1, microtubule-associated protein 1A/1B-light chain 3(LC3) Ⅱ/Ⅰ, and MyD88/TLR4/NF-κB p65 pathway related proteins in lung tissue. Results Compared with control group, knee joint tissue and lung tissue of rats in RA-ILD group were damaged, the arthritis index, lung tissue wet-dry weight ratio, levels of IL-1β, IL-6, and TNF-α, the expression levels of MyD88 and TLR4 proteins, and p-NF-κB p65/NF-κB p65 ratio increased(P