Abstract: Effects of exogenous spermidine application(0.1 mmol/L) on plant growth, root feature parameters(root length, root surface, root volume etc.), relative water content of leaf, chlorophyll contents and membrane permeability in seedlings of maize cultivar ‘Xianyu 335’(drought-tolerant) and ‘Fenghe No.1’(drought-sensitive) under drought stress induced by 20% polyethylene glycol 6000 were investigated by hydroponic experiments. The results showed that exogenous spermidine significantly increased the fresh and dry weight, plant height, root length and root surface of both maize seedlings, but only slightly affected the root volume, average root diameter, relative water content of leaf, chlorophyll contents and membrane permeability under normal condition. When under drought stress, exogenous spermidine treatment could lead to a marked increase in fresh and dry weight, plant height, relative water content and chlorophyll contents of leaf, increase the number of roots, with the increase of the number of roots of 0-1.00 mm diameter class, the increase of root length corresponding to is large, and with the number of roots of 0.50-1.50 mm diameter class increases, the corresponding increase of the surface area is great, and decrease leaves membrane permeability of maize seedlings. The effect of exogenous spermidine on anti-aging was more obvious in drought-sensitive Fenghe No.1 than in Xianyu 335 maize variety. The results suggested that appropriate amount of exogenous spermidine could lighten the drought stress damage and alleviate the growth inhibition of drought-sensitive maize variety.