The present study was undertaken to evaluate the effect of flavonoids from Lotus (Nelumbo nuficera Gaertn) leaf (FFL) on exhaustive swimming exercise-induced oxidant stress by measuring related biochemical parameters of mice. 32 male mice were randomly divided into four groups: control group, FLL low dose treated group, FLL middle dose treated group and FFL high dose treated group. The control group was given distilled water and the treated groups were given different doses of FLL (50, 100, 150 mg/kg) by gavage once a day for 28 days. 28 day later, mice were made to swim until being exhausted, then the exhaustive swimming time and some biochemical parameters related to oxidative stress were measured. The data showed that FFL can extend the exhaustive swimming time of the mice, as well as increasing the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities, but decrease the malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels. These results indicated that FLL possessed protective effects against exhaustive swimming exercise-induced oxidative stress.