Abstract:In this experiment, the effect of ABA on the cold resistance of tobacco seedlings was investigated to provide a theoretical basis for improving cold-resistance during seeding stage and cold-resistance breeding. YY 87 was selected as the material, ABA was sprayed on the leaves under 15℃ temperature of cold stress. The physiological indexes, including content of soluble protein, soluble sugar, proline, malondialdehyde(MDA), SOD, POD, CAT activity, content of chlorophyll and chlorophyll fluorescence parameters were detected to analysis the cold resistance of tobacco seedling. Spraying ABA under cold stress conditions significantly increased the contents of soluble protein,soluble sugar, and proline compared to the control. It also slowed down the accumulation of MDA content, while increase the activity of SOD, POD, CAT significantly, stop the decrease of the content of chlorophyll effectively, which would reduce the influence of low temperature on photosynthesis of plant leaves. The root activity was also improved, which result in maintaining the biomass accumulation in high level of tobacco seedlings. Spraying the ABA on tobacco under low temperature can effectively raise the ability of cold resistance of tobacco seedling.