Objectives: Rheumatoid arthritis (RA) seriously affects the daily life of people. The whole plant of Artemisia ordosica Krasch. (AOK) has been used in folk medicine. This study aimed to investigate the in vivo anti-RA effects of AOK extract (AOKE) on collagen-induced arthritis in rats., Methods: AOKE (400, 200, or 100 mg/kg) was administered orally to animals for 30 days. Body weight, paw swelling, arthritis index, thymus, and spleen indices, and pathological changes were assessed for effects of AOKE on RA. Furthermore, the inflammatory cytokines in rat serum were detected. In addition, the expressions of STAT3, Caspase-3, Galectin-3, and S100A9 in synovial tissue were researched using immunohistochemistry., Key Findings: The AOKE significantly reduced the arthritis indices, paw swelling, spleen, and thymus indices. Meanwhile, AOKE (400 mg/kg) decreased the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-17A, and increased the level of IL-10 in rat serum. Histopathological examination showed that AOKE reduced inflammatory cell infiltration and cartilage erosion. Then, AOKE decreased the expressions of STAT3, Galectin-3, S100A9, and increased the expression of Caspase-3., Conclusion: AOKE had interesting anti-RA activity in rats, which deserved further research for the development and clinical use of this medicinal resource., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)