Objective: To investigate the antitumor effect of different doses of artemisinin on human gastric cancer cell line SCG-7901 subcutaneous transplanted tumor in nude mice and its mechanism. Methods: A subcutaneous transplantation tumor model of human gastric cancer nude mice was established and randomly divided into experimental groups, i.e., 100 mg/kg for artemisinin low-dose group, 150 mg/kg for artemisinin medium-dose group and 200 mg/kg for artemisinin high-dose group, and 20 mg/kg for blank control saline group and positive control 5-FU group, which were administered by gavage for 10 days, and the nude mice were executed 24 hours after stopping the drug, and the tumor weights were weighed, The tumor inhibition rate was calculated, and the apoptosis rate and Caspase-3 activity were detected by flow cytometry. Results: The tumor inhibition rate of high, medium and low dose artemisinin group and 5-Fu group were 71.37%, 47.74%, 31.31% and 45.17%, respectively, which were statistically significant compared with saline group, and the difference of tumor inhibition rate between low dose group and 5-Fu group was P=0.457<0.05, which was statistically significant; however, the tumor inhibition rate could be seen that the low dose group of artemisinin was less effective than 5-Fu group. The effect of artemisinin was poorer than that of 5-Fu group. The caspase-3 activity was found to increase gradually with the increase of artemisinin dose, with the most significant increase in the high-dose artemisinin activity. Conclusion: Artemisinin can exert anti-tumor effects in vivo by activating Caspase-3 to induce apoptosis.