Abstract: The effects of allicin at different concentrations on seed germination and seedling growth of Chinese cabbage, radish and lettuce were investigated using seed soaking and foliar spraying methods. Results showed that Allicin had some effects on seed germination of cabbage, radish and lettuce by soaking method, there were differences between crops and varieties. Allicin at the concentration of 200 mg/L soaked for 12 hours had no adverse effects on seed germination of radish and lettuce, but could delay seed germination of cabbage, reduce seed germination energy and germination index, had no effect on final germination rate. Allicin at the concentrations of 400 and 800 mg/L soaked for 12 hours could delay seed germination of cabbage and radish, and reduce its seed germination rates, germination energies and germination indexes, which its activity decreased with increased concentration. Then, the final germination rates of cabbage and radish were significantly reduced, but no effects on final germination of lettuce occurred. Allicin had significant promoting effects on seedling fresh weight, root fresh weight and hypocotyl width of cabbage at the concentrations of 200 mg/L soaked for 12 hours, had no significant promoting effects on those at the concentrations of 400 and 800 mg/L, but there were a significant difference between varieties, seedling main root and hypocotyl length shortened with increased concentration. Allicin could significantly promote seed germination, seedling fresh weight, root fresh weight and hypocotyl width of radish, significantly inhibited its main root and hypocotyl growth at the concentrations of 200 and 400 mg/L soaked, and significantly inhibited the seed germination of radish at the concentrations of 800 mg/L soaked. Allicin at the concentrations of 200 to 800 mg/L soaked could promote seed germination, seedling fresh weight, root fresh weight and hypocotyl width of lettuce, and had obvious inhibitory effect on main root and hypocotyl length. Allicin at the concentrations of 200 to 800 mg/L sprayed had obvious promoting effect on seedling growth of 3 kinds of vegetable, mainly in the seedling fresh weight and root fresh weight increased, plant height and hypocotyl width increased, and had obvious inhibitory effect on main root growth, but there was not significant difference between different concentrations.