Abstract: To study the anti-fatigue effect of Spirulina polysaccharide. One hundred male mice of BALB/c were randomly divided into low dose group, middle dose group, high dose group, blank contrl group and positive control group, three rose groups were administered Spirulina polysaccharide at 100, 200, 300mg/kg body weight, respectively, blank contrl group and positive group were administered physiological saline and American ginseng powder at 500mg/kg body weight. The control group was administered with normal saline by gavage every day for 30 days. Weights in each group of mice were measured every three days. The climbing time, exhaustive swimming time, the blood lactic acid (BLA) , blood urea nitrogen (BUN) , the activity of lactate dehydrogenase (LDH) , muscle glycogen (MG) content and liver glycogen (LG) content in each group of were measured after 30 days. Results showed that all three dose groups could extended climbing and weight-loaded swimming time of mice, comparing with blank control group, middle and high dose groups could effectively decrease the level of BLA and BUN, enhance the activities of LDH, increase in liver and muscle glycogen deposition. In conclusion, Spirulina polysaccharide had obvious effect on anti-fatigue.