Abstract: A key of afforestation in vast sand areas of China is moisture, which is why the relations between xerophyte and water have been considered as one of most important subjects in fixed positions since the establishment of Deng-kou Experimental Station in 1979. The water supply and consumption as well as physiological conditioning function of plants in draught environment are known by analysis of dynamic characteristics of groundwater that is reliable for plant living in sand areas and measurement of main plant physiological index-plant transpiration, water potential and adhesive water. Then suitable environment planting Haloxylon ammodendron and Hedysarum mongolicurn are determined. The research suppliss scientific data for classification of sites and selecting tree species in dry sandy areas also.