Abstract: The relative root activity,leaf cell permeability,SOD activity,MDA contents and seedling growth of Pteroceltis tatarinowii,Taxodium distichum and Fraxinus velutina under drought conditions were studied.The abilities to droughtresistance of these species were compared and the main conclusions were drawn as follows:The order of relative root activity was P.tatarinowii,F.velutina and T.distichum;The order of leaf relative conductivity rates was:P.tatarinowii＜F.velutina＜T.distichum;The SOD activity was in order of P.tatarinowii,F.velutina and T.distichum;The MDA contents was in order of P.tatarinowii,F.velutina and T.distichum;The effects of drought stress on their growth were in order of P.tatarinowii,F.velutina and T.distichum.The conclusions shew that their abilities to drought stress was in order of P.tatarinowii,F.velutina and T.distichum.