Abstract: In this study,the mouse colitis model was induced by dextran sulfate sodium(DSS),and the inhibitory effects of Lactobacillus plantarum YS-2(LP-YS2)were observed. The experimental mice were divided into normal group,model group,LP-YS2-L group,LP-YS2-H group and sulfasalazine group,the other groups except the normal group mice were induced colitis,meanwhile,LP-YS2-L group,LP-YS2-H group and sulfasalazine group mice were administered daily 0.2 mL 1×10⁸ CFU/mL LP-YS2,1×10⁹ CFU/mL LP-YS2 and 20 mg/kg sulfasalazine,for 5 weeks. Then the colonic morphology of mice were determined by H&E section observation,the serum and colon tissues of mice colon were determined using kits endothelin(ET),somatostatin(SS),substance P(SP),vasoactive intestinal peptide(VIP),myeloperoxidase(MPO),glutathione(GSH),malondialdehyde(MDA),superoxide dismutase(SOD),interleukin-2(IL-2),interleukin-10(IL-10),and the mRNA expression of neuronal nitric oxide synthase(nNOS),endothelial nitric oxide synthase(eNOS),inducible nitric oxide synthase(iNOS),c-Kit,stem cell factor(SCF),interleukin-8(IL-8),chemokine(C-X-C motif)receptor 2(CXCR2)were determined by fluorescent quantitative PCR technique. The experiment results showed that compared with the model group,LP-YS2 could significantly(p<0.05)increase colon length and the ratio of colon weight/colon length in colitis mice(model group). The detection of mice serum showed that LP-YS2 could significantly(p<0.05)reduce the serum levels of ET,SP,IL-10,and significantly(p<0.05)increase the levels of SS,VIP and IL-2 in colitis mice(model group). The detection of colon tissue showed that LP-YS2 could significantly(p<0.05)raise the GSH content,SOD activity and significantly(p<0.05)reduce the MPO activity,MDA content in the colon of colitis mice(model group). LP-YS2 could also significantly(p<0.05)up regulate the mRNA expression of nNOS,eNOS,c-Kit,SCF,and significantly(p<0.05)down regulate the expression of iNOS,IL-8,CXCR2 in the colon of colitis mice(model group). From these results,it coul be seen that LP-YS2 had the effects of colitis suppression.