Abstract: ［Abstract］Objective　To investigate the inhibitory effects of flavonoid isolated from the leaves of Acer truncatum Bunge on the expression of pro-inflammatory cytokines in Raw264.7 cells stimulated with lipopolysaccharide （LPS）．Methods　Inflammatory cell model was structured by LPS-stimulated Raw264.7 cells，the cells were treated with flavonoid（10 μM， 30 μM and 60 μM） prior to LPS（5 mg/mL）exposure and the effects of flavonoid on viability of Raw264.7 cells were measured by MTT assay，Nitric oxide（NO）and prostaglandin E2 （PGE2）were measured by ELISA，the effects on the protein levels of pro-inflammatory enzymes，cyclooxygenase-2（COX-2）and inducible nitric oxide synthase（iNOS），and pro-inflammatory cytokines，tumor necrosis factor-α（TNF-α），and interleukin-1β（IL-1β），inflammatory signaling proteins nuclear factor-κB （NF-κB）were analysed by immunofl uorescence staining assay．Results　LPS-induced NO，PGE2，iNOS， COX-2 and NF-κB protein expression levels were significantly decreased by flavonoid in a concentration-dependent manner and flavonoid also had an effect on the expression of TNF-α，IL-1β through translational inhibition． Conclusion　Flavonoid isolated from the leaves of Acer truncatum Bunge can inhibit LPS-induced activation of Raw264.7 cells through inhibiting the release of pro-infl ammatory mediators，then exerts its anti-osteoporosis activities.