Based on a synthesis of the literatures on Ecological water requirement of vegetation (EWRV), the conceptions and meanings of EWRV were systematically reviewed in this paper. The Ecological appropriate theory, the system threshold theory, the water cycle-balance theory and the agro-meteorology theory were introduced in detail at the beginning of the paper, and then their corresponding advantages and disadvantages in the practical application were also examined. It was also pointed out that researches about healthy standards of ecological system; multidisciplinary research; numerical simulation model of EWRV in quantitative evaluated index system should be intensified in the future. At the same time, future research will be focused on spatial-temporal characteristic of EWRV. In order to provide a great deal of reliable data for the theory research of EWRV, the basic databases of different regions must be obtained at various orientations and angles by using “3S” technology and advanced equipment.