Objective:　To　investigate　the　effect　of　alginate　oligosaccharides　(AOS)　on　dextran　sulfate　sodium　(DSS)-induced　inflammatory　bowel　disease　(IBD)　in　mice　and　to　explore　the　possible　mechanism　based　on　the　effect　of　AOS　on　the　intestinal　flora　and　short-chain　fatty　acids　(SCFAs).　Methods:　Male　C57BL/6　mice　were　provided　with　1.5%　DSS　for　5　days　for　acute　colitis　modeling.　Meanwhile,　mice　were　orally　administrated　with　gradient　doses　of　AOS　(0.5,　1,　and　1.5　g/kg)　for　9　days.　On　day　10,　body　mass,　colon　length,　disease　activity　index　(DAI),　and　tissue　damage　were　assessed.　Polymerase　chain　reaction　was　used　to　assess　the　mRNA　expression　levels　of　tumor　necrosis　factor-α　(TNF-α),　nuclear　factor　kappa　B　(NF-κB),　interleukin-6　(IL-6),　IL-1β,　the　tight　junction　protein　zonula　occluden-1　(ZO-1)　and　G　protein-coupled　receptor　43　(GPR43).　SCFAs　production　was　measured　by　high　performance　liquid　chromatography　(HPLC)　and　the　microbial　community　was　analyzed　by　high-throughput　sequencing.　Results:　AOS　significantly　alleviated　the　symptoms　of　colitis,　such　as　body　mass　loss,　colon　shortening,　and　tissue　damage,　and　reduced　the　mRNA　expression　of　TNF-α,　NF-κB,　IL-6　and　IL-1β,　while　increasing　the　expression　levels　of　ZO-1　and　GPR43.　Additionally,　AOS　significantly　increased　the　number　of　Propionibacterium,　while　inhibiting　the　growth　of　Enterococcus　and　Actinomyces;　high-dose　AOS　also　enhanced　the　production　of　colonic　lactate,　acetate,　and　propionate.　Conclusion:　AOS　play　a　positive　role　in　ameliorating　DSS-induced　colitis　in　mice,　and　the　effect　may　be　associated　with　the　regulation　of　the　intestinal　flora　and　SCFAs.　Hence,　AOS　have　the　potential　as　a　functional　food　ingredient　to　alleviate　intestinal　inflammation.　©　2025,　Chinese　Chamber　of　Commerce.　All　rights　reserved.