Atractylodes lancea (Thunb.) DC (AL) has been extensively used in dietary health and clinical treatments due to its beneficial therapeutic effects on the gastrointestinal tract. In this study, we isolated and purified AL polysaccharide (ALP) and investigated its therapeutic efficacy in chemotherapy-associated gastrointestinal damage. The primary constituents of ALP, ALP-3, are predominantly composed of Glc and Fru, interconnected by →1)-β-D-fruf-(2→, with a minor proportion of β-D-Fruf-(2→, α-D-Glcp-(1→), which form the main chain, and a molecular weight of approximately 10.696 kDa. Then, the mice were subjected to cisplatin-induced gastrointestinal damage, and the protective effects of ALP-3 were evaluated in this model. We found that the ALP-3 possesses strong anti-inflammatory, antioxidant, and restorative properties in repairing the intestinal barrier. Additionally, ALP-3 significantly enhances the abundance of Lactobacillaceae and Lactobacilli, while simultaneously reducing the prevalence of Bacteroides and Escherichia-Shigella, and decreasing LPS-induced TLR4 activation. Our findings suggest that ALP-3 may be used as a preventive compound for preventing and ameliorating gastrointestinal damage induced by chemotherapy.