BACKGROUND: Clematichinenoside AR (CAR) is an effective monomer component of Clematis chinensis Osbeck, which has therapeutic effects on rheumatoid arthritis (RA), but its specific mechanism is still not fully elucidated. PURPOSE: This study elucidated whether CAR alleviated RA by inhibiting synovial angiogenesis and revealed its molecular mechanism. METHODS: Arthritis indicators and H&E staining were used to evaluate the therapeutic effects of CAR on collagen-induced arthritis (CIA) rats, and the IHC, IF, EdU-Hoechst, tunel, flow cytometry, wound healing and transwell assay were used to investigate the effects of CAR on synovial angiogenesis. The co-culture model of RA fibroblast-like synoviocytes (FLSs) and human umbilical vein endothelial cells (HUVECs) was established. Tube formation, western blot, RT-qPCR and other related methods were used to evaluate the specific mechanism of CAR. RESULTS: CAR alleviated arthritis pathology and inhibited angiogenesis in CIA rats. CAR inhibited the proliferation, migration and invasion of RA FLSs, and promoted their apoptosis. Importantly, overexpression of HIF-1α inversed the inhibitory impact of CAR on the expression of HIF-1α, VEGFA, VEGFR2, and ANG2, as well as the inhibitory effects of CAR on the expression of CD31/34 and the HUVEC tube formation. Molecular docking, molecular dynamics, and experimental verification confirmed that CAR has a strong binding affinity with HIF-1α, further indicating that HIF-1α was a target of CAR for anti-angiogenesis. CONCLUSION: CAR had a good inhibitory effect on RA, and its mechanism was inhibition of synovial angiogenesis through the HIF-1α/VEGF/ANG2 axis.