Water is the main environmental factor that affects plant growth and survival, and the eco-physiology of plants involving water has been an important aspect of research in plant drought resistance for a long time. The emergence of the PV technique allows researchers to investigate the water status of plant tissues in greater detail and to investigate the potential resistance of plants to drought resistance with new approaches. However, the application of the PV technique to the study of drought resistance in plants also brings about other problems such as the abuse of the method. Because the resistance of plants to drought stress is a process of regulated through multiple pathways, it is very hard to evaluate the drought resistance of plants with a single index or parameter. Thus the attempt to look for a eco-physiological index of water that is more accurate and more reasonable in evaluating the drought resistance of plants is a goal sought by researches for many years. In this experiment, the parameters of plant water status were measured by means of the PV curve, and the transpiration rate, leaf and/or twig water potential, and their osmotic potential were measured with a TPS-1 photosynthesis system, a pressure chamber and a dew point microvolt-meter in 5 woody plants (Populus euphratica Oliv., Elaeagnus angustifolia L., Tamarix ramosissima Ledeb., Haloxylon ammodendron Bunge, Hedysarum scoparium Fisch.) living in arid zone, respectively. The water status in relation to their drought resistance in the 5 woody plants were analyzed in terms of ψ_s^sat (the osmotic potential in water saturated), ψ_s^tlp (the osmotic potential when turgor pressure is zero), RWC^tlp (the relative water content when turgor pressure is zero), ROWC^tlp (the relative content of osmotic water when turgor pressure is zero), V_a (the content of bounding water), transpiration rate, water potential, osmotic potential, water-retaining capability and relative water content. The results showed that although parameters from the PV curve could reflect the water status of in plant tissue and their potential drought resistance, the extent of resistance showed by those parameters is different or even contradictory. The drought resistance indices calculated with membership function based on the 5 parameters from the PV curve (ψ_s^sat, ψ_s^tlp, RWC^tlp, ROWC^tlp and V_a) showed that there was no significant difference in drought resistance in the 5 woody plants living in arid zone; while the comprehensive indices of drought resistance yielded from the combined analysis of the parameters from the PV curves, transpiration rate, leaf/twig water potential, osmotic potential, water-retaining capability and relative water content showed that the 5 species can be divided into 3 levels in terms of drought resistance: the first is H. ammodendron with the highest drought resistance; the second is T. ramosissima, and E. angustifolia, H. scoparium, and P. euphratica belong to the third category, among which P. euphratica having the lowest drought resistance duo to its high level of water consumption that narrows its habitats progressively. It is therefore concluded that a comprehensive estimation of the parameters from the PV curves (ψ_s^sat, ψ_s^tlp, RWC^tlp, ROWC^tlp and V_a) and from the actual measurements (transpiration rate, water potential, osmotic potential, water-retaining capability and relative water content) could better evaluate the drought resistance of plants.