Vegetation is an important part of the ecosystem, so it is necessary to study the changes of vegetation soil moisture in arid regions. In this study, Xinjiang, a typical arid region in Northwest China, was selected as the study area. Based on the total primary productivity (TPP) and land cover type data from MODIS remote sensing data, soil moisture reanalysis data from ERA5, and precipitation and potential evapotranspiration data from CRU, the soil moisture in Xinjiang was calculated over a 20-year period. Combined with the collected data, a simulation analysis of vegetation ecological water demand in Xinjiang over a 20-year period was carried out based on vegetation and soil information, as well as a vegetation ecological water demand model. The mean value of soil moisture limiting coefficient in Xinjiang has a small range of variation, fluctuating around between 0.344 and 0.402. The ecological water demand per unit area of grasses, shrubs, and trees at the full fertility stage varied in the ranges of 51-106 mm, 125-247 mm, and 181-393 mm, respectively, with trees having a larger water demand. The water content of different types of soil in the arid zone was ranked as: Mobile sandy land > arid 2-year sandy land > arid 5-year sandy land > naturally restored land > artificial + naturally restored land > artificially restored land, and moisture-rich soils were able to maintain a high level of species diversity. The results of this paper provide very positive guidance for the scientific management of ecosystems in Xinjiang.