The experiment was conducted to evaluate the effect of Aspirin on animal immune function by studying the effects of different doses of Aspirin on the lymphocyte activity in mice blood and spleen. Forty eight Kunming mice (20±2g) were selected and assigned randomly to 4 groups to finish the experiment. The treatment contained low-dose (10mg/k g•bw), middle-dose (20 mg/k g•bw), high-dose (40 mg/k g•bw) Aspirin group and blank control group. T he experimental stage was 20 days. On the 10 th and 20 th day in the trial, 6 mice were chosen randomly to be sampled and the indexes were determined. The activity of lymphocyte in low and middle dos e groups were enhanced and the activity of lymphocyte in middle dos e group was higher than that in low dos e group, but there was no significant difference (p>0.05). On the 20 th day in the trial, the activity of lymphocyte in spleen in middle dose group was significantly higher than that in control group (p<0.05). On the 20 th day in the trial, the activity of lymphocyte in spleen in middle dose group was significantly higher than that in control group (p<0.05). During the course of the trial, during the course of the trial, the activity of lymphocyte in blood and spleen in high dose group de creased, but there was no the activity of lymphocyte in blood and spleen in high dose group decreased, but there was no significant difference (p>0.05). This indicated that proper dose of Aspirin could enhance the activity of lymphocyte in mice significant difference (p>0.05). This indicated that proper dose of Aspirin could enhance the activity of lymphocyte in mice.