Based on the present situation of Minqin desert oasis, this paper summarizes the relevant research results at home and abroad, and clarifies the connotation of ecological water demand, which is based on vegetation growth. Starting from the suitability, threshold, circulation and agrometeorology of ecosystem, this paper analyzes the theoretical basis of vegetation ecological water demand, and puts forward the ecological water demand estimation method suitable for Minqin oasis, that is, based on the 3S technology to divide the land type and area, mainly by using diving evaporation method, comprehensively use the direct calculation method, Penman-Monteith formula and other calculation methods. In addition, the difficulties in the study of vegetation ecological water demand are discussed, and the emphasis should be placed on establishing the response function of vegetation growth, rainfall, and groundwater depth, exploring the coupling mechanism of diving and SPAC system, and revealing the mechanism of vegetation ecological water demand.By constructing the index system of suitable vegetation degree and hydrological ecological conditions in Minqin desert oasis, and exploring the mechanism of vegetation ecological water demand, we will ultimately achieve the coordinated and sustainable development of population, resources, environment and economic society.