Interleukin-1 beta (IL-1 beta) plays a central role in the induction of rheumatoid arthritis (RA). In the present study, we demonstrated that lipidoid-polymer hybrid nanoparticle (FS14-NP) can efficiently deliver siRNA against IL-1 beta (siIL-1 beta) to macrophages and effectively suppress the pathogenesis of experimental arthritis induced by collagen antibody (CAIA mice). FS14-NP/siIL-1 beta achieved approximately 70% and 90% genesilencing efficiency in the RAW 264.7 cell line and intraperitoneal macrophages, respectively. Intravenous administration of FS14-NP/siRNA led to rapid accumulation of siRNA in macrophages within the arthritic joints. Furthermore, FS14-NP/siIL1 beta treatment lowered the expression of pro-inflammatory cytokines in arthritic joints and dramatically attenuated ankle swelling, bone erosion, and cartilage destruction. These results demonstrate that FS14-NP/siIL-1 beta may represent an effective therapy for systemic arthritis and other inflammatory disorders.