Abstract: Objective: To study the anti-fatigue effects of mulberry anthocyanins (AM) and discuss the mechanism in mice. Methods: After preparation and analysis, the the antioxidant activity AM was evaluated. The mice were randomly divided into the quiet group, the aerobic exercise group, the model group, the low, medium and high does groups (the AM dosage were 100, 200 and 400 mg/kg/d, respectively), and exhaustive swimming test were performed. After mouse were orally administered for 4 weeks, the fatigue-related biochemical indicators were measured to evaluate the anti-fatigue effect of AM, such as the levels of blood lactic acid (Lac), blood urea nitrogen (BUN) and malondialdehyde (MDA) the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Meanwhile, the anti-fatigue mechanism was explained by the relative expression levels of Nrf2 and HO-1 mRNA. Result: After enrichment and purification, the contents of active components in AM were increased, and showed the antioxidant capacity that equivalented to vitamin C. Compared with the model group, the low, medium and high does groups were significantly prolonged exhaustive swimming time (P<0.05), as well as the exercise capacity was increased. The medium and high does of AM significantly decreased the levels of Lac and BUN (P<0.05), the activities of LDH and CK (P<0.05) in rat blood, improved the activity of SOD and GSH-Px, as well as low-regulate the level of MDA, 8-OHdG and ROS (P<0.05) in muscle. Furthermore, AM significantly increased the expression levels of Nrf2/HO-1 mRNA in muscle (P<0.05). Conclusion: AM could improve the ability of the antioxidant capacity to exert anti fatigue effect through regulating Nrf2/HO-1 signaling pathway.