To observe the effects of allicin on the growth and apoptosis of gastric cancer cell line. The viability of gastric cancer cell line SGC-7901 was determined by MTT, cell morphology was observed under AO staining and electron microscopy, the apoptosis was measured using flow cytometry analysis. The results indicated that the growth of gastric cancer cell line SGC-7901 was significantly inhibited by allicin, and the IC50 was 80µg/mL. Morphological variations of apoptosis were observed at 48 hours treated with allicin by AO staining and apoptosis body was observed under electron microscope. The results indicated that allicin can suppress the growth of gastric cancer cell line SGC-7901 and induce apoptosis of the cells.