Abstract: The photosynthetic and water physioecological characteristics of four dominant species, Caragana microphylla,Artemisia halodendron,Artemisia frigida and Populus spp(a hybird),in Kerqin sandy land were compared.The photosynthesis rates of C.microphylla,A.halodendron, and Populus spp. reached highest at 6◇00,rapidly fall at 8◇00,remained at low level from 8◇00 to 16◇00,then rose slowly after 16◇00.The photosynthesis rate of A.frigida was comparatively low at 6◇00,so the range of declining speed was small.Diurnal photosynthesis rate of Artemisia frigida decreased at 6◇00～8◇00, C.microphylla at 8◇00～10◇00, Populus spp and. A.halodendron at 6◇00～ 10◇00,and was controlled by stomatal limitation;in rest time,it was controlled by non-stomatal limitation.The four species also adapted different ways to resist drought stress. C.microphylla and A.frigida resisted drought stress through their low transpiration,low water potential and high ratio of bound water to free water(BW/FW); Populus spp.resisted drought stress through its rapid fall of stomatal conductivity to reduce its transpiration in spite of its high water potential and high BW/FW,while A.halodendron resisted drought stress weakly because of its high transpiration,high water consumption and low water use efficiency.