This study showed that L. plantarum L15 prevented DSS-induced colitis by reducing pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and elevating anti-inflammatory cytokine(IL-10)level, up-regulating the mRNA expression level of tight junction protein (ZO-1, Occludin, Claudin-1) and mucin (MUC2), and decreasing D-lactic acid and LPS. The gene discussed is TNF; the disease is colitis.