Abstract: OBJECTIVE： To study synergistic anti-fatigue effect of different doses and combinations of American ginseng and astragalus，and to screen out the dose with significant anti-fatigue effect. METHODS： American ginseng and astragalus were extracted with water and precipitated with alcohol at a ratio of 1∶3， and the precipitate was dried to obtain the herbal extract. The extract was administered to mice by gavage at high，medium，and low doses (600，300，and 150 mg/kg，respectively) for 30 days. A blank control group and a positive control group were also set up. The fatigue resistance of animals in different dose groups was judged by lactate clearance rate test， serum urea nitrogen and creatine kinase content after exercise， liver glycogen content，and changes in related indicators in the weighted swimming test. RESULTS： Compared with the blank control group，each test group showed a reduced area under the curve of serum lactate，increased liver glycogen content， reduced serum urea nitrogen and creatine kinase levels after exercise and increased time to exhaustion in the weighted swimming test (P<0.05 or P<0.01). Compared with the positive control group， the area under the curve (AUC) of blood lactate and the liver glycogen content of mice in the high-dose test substance group were decreased (P<0.01). CONCLUSION： The American ginseng and astragalus combination had an anti-fatigue effect on mice，and the high-dose group has a better anti-fatigue effect than the positive control.

Key words: American ginsengt, astragalus, anti-fatigue, mice