To observe the anti-fatigue effect of Yuzhuoqing Granules and its mechanism on rats.Methods:Forty mice of Kunming breed randomly allocated, received lavage respectively with physiological saline, Princens extraction, low dose and high dose of the granules for 10 days. To mount lead as heavy as 10% body weight onto the mice' tails, and observe the swimming duration till mice sank.Results:Both granule-treated groups showed significantly longer swimming duration than the blank group (P<0.05, P<0.01); While the mean time value of the high dose group was significantly longer than that of the positive control group (P<0.05).Conclusion:Having prolonged swimming duration in the experiment, it was concluded that Yuzhuoqing Granules can improve physical endurance and fight fatigue.