Ebosin is a novel exopolysaccharide produced by Streptomyces sp.139 with remarkable activity against rheumatic arthritis in vivo.  In this paper, we reported effects of Ebosin on the inflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor α (TNFα) in THP-1 cells.  With the special fluorogenic peptide as substrates, the enzymatic activities of interleukin-1β converting enzyme (ICE) and TNFα-converting enzyme (TACE) were inhibited by Ebosin separately.  Using the real-time reverse transcription polymerase chain reaction (real-time PCR), the mRNA synthesis of the three cytokines were identified decline separately by Ebosin.  The secretion quantum of three cytokines in THP-1 cells with Ebosin was lower than that of normal THP-1 cells determined by ELISA assay and Western blotting.  All of these results showed that Ebosin has remarkably suppressed synthesis of the three cytokines in THP-1 cells through different pathways.  The primary study of Ebosin on anti-inflammation mechanism was promoted developing the new drugs treating rheumatic arthritis.