Abstract: Objective: To investigate the effect of Tremella fuciformis polysaccharides (TFP) on oxidative damage induced by exhaustive exercise in mice and analyze its mechanism. Methods: L6 cells were treated with TFP for 48 hours, and the activity of L6 was detected by CCK-8 method. L6 cells were divided into three groups, including the control, H₂O₂, and H₂O₂+TFP groups, and incubated for 48 hours. LA levels were measured by a biochemical analyzer, and Nrf2, NQO1, and HO-1 protein levels were detected by Western blot assay. C57BL/6 mice were randomly divided into four groups (n=10 for each group), including model group and model+TFP group (50, 100, 200 mg/kg). The model+TFP groups were continuously gavaged with TFP, while the model group was gavaged with the same dose of distilled water once a day for two consecutive weeks. Exhaustive exercise was performed 30 minutes after the last administration, the duration of exhaustive swimming exercise was recorded, and enzyme-linked immunosorbent assay (ELISA) was used to detect liver glycogen (LG) and skeletal muscle glycogen (MG). ELISA was used to detect blood urea nitrogen (BUN), lactic acid (LA), ROS, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), TNF-α, IL-6 and NF-κBp65 levels. Western blot assay was used to detect the levels of Nrf2, NQO1, and HO-1 proteins. Results: The LA levels of L6 cells in the H₂O₂ group were significantly (P<0.01) higher than those in the control group, while the protein levels of Nrf2, NQO1, and HO-1 were significantly (P<0.01) lower than those in the control group. TFP could significantly (P<0.01) reduce the LA levels in the culture medium and upregulate the expression of Nrf2, NQO1, HO-1 in L6 cells. TFP could significantly prolong exhaustive swimming time (P<0.01), reduce LA (P<0.01) and BUN (P<0.05, P<0.01) levels, increase liver and muscle glycogen levels (P<0.05, P<0.01), upregulate SOD (P<0.01) and GSH-Px (P<0.01), downregulate MDA (P<0.05, P<0.01) and ROS (P<0.01) levels, and reduce TNF-α (P<0.01), IL-6 (P<0.01) and NF-κBp65 (P<0.01). Compared with the model group, TFP could significantly increase Nrf2 (P<0.05, P<0.01), HO-1 (P<0.05, P<0.01) and NQO-1 (P<0.05, P<0.01) protein expression levels. Conclusion: TFP improved oxidative damage caused by exhaustive swimming by inhibiting oxidative stress and inflammation, and its mechanism was related to regulating the Nrf2/HO-1 signaling pathway.