Vegetation is an important component of terrestrial ecosystems and plays a key role in maintaining ecosystem stability. The study of the ecological water requirements in vegetation has become a hot issue in research of water resources allocation and ecol-environmental construction. On the basis of the comprehensive analysis of previous research results, this study introduced the concept of ecological water requirements of vegetation and also reviewed the advantages and disadvantages of several methods for estimating ecological water requirements of vegetation in arid and semi-arid regions, including the quota-area method, the phreatic evaporation method, the plant evapotranspiration method, the water balance method, the biomass method and the method based on remote sensing technology. The results of this study emphasized that it is necessary to pay much attention to the research of the application of “3S”, numerical modeling and scale transformation in the calculation of ecological water requirements of vegetation in the future.