Abstract: To investigate the fermentation of the modified kidney bean dietary fiber influence on sports ability exercise fatigue, The experiment using modified kidney bean dietary fiber composite strains fermentation, the determination of its physical and chemical properties before and after fermentation was researched. And the motility of rats model was established with different doses of kidney bean dietary fiber (5.80, 2.90, 1.45 g/kg) by swimming exhaustion experiments. The changes of urea nitrogen, malondialdehyde, lactate dehydrogenase, superoxide dismutase, glutathione peroxidase, liver glycogen and muscle glycogen were analyzed to explore their effects on exercise-induced fatigue. The results showed that the dietary fiber content of modified kidney bean was 18.32%, and the water holding capacity, swelling capacity and oil holding capacity were increased by 144.83%, 80.66% and 58.97%, respectively. Compared with model group, the high, medium and low dose group could prolong swimming exhaustion time, reduce the MDA content (P<0.05), improve the SOD and GSH-Px activity (P<0.05), and improve the muscle glycogen and the content of hepatic glycogen and store capacity. The effect of high dose group was the most significant (P<0.05). In conclusion, fermented modified kidney bean dietary fiber had a positive effect on anti-exercise fatigue, and could improve antioxidant capacity, protect muscle tissue and enhance exercise tolerance. It was of great significance to use human body as a kind of exercise nutritional supplement in the future.