The Turpan-Hami region in Xinjiang, commonly referred to as the "Tuha region," is renowned for its severe arid conditions, prolonged sunshine hours, significant diurnal temperature fluctuations, and a delicate ecological balance. Consequently, ecological and environmental concerns loom large in this region, where the judicious utilization of water resources holds the key to safeguarding its ecological integrity. Vegetation ecological water demand constitutes a significant chunk of the overall water demand in the Tuha region, crucial for maintaining regional ecological stability and fostering sustainable development.This study, premised on the classification of ecological protection importance, delved into the analysis of the total vegetation area and the specific vegetation area within each ecological protection grade in the study area. Three methodologies - the modified Penman formula method, the phreatic evaporation method, and the ecological zoning comprehensive calculation method - were deployed to estimate the vegetation ecological water demand in various ecological protection grades in the Tuha region, spanning from 1990 to 2020.The findings revealed intriguing insights: (1) The total vegetation ecological water demand in the Tuha region, estimated using the trio of methods, exhibited fluctuations during the period of 1990-2020. Precisely, the modified Penman method pegged it at a range from 5.018 billion cubic meters to 5.78 billion cubic meters, the phreatic evaporation method estimated it to be between 5.442 billion cubic meters and 5.185 billion cubic meters, while the ecological zoning method arrived at a range of 4.558 billion cubic meters to 5.203 billion cubic meters. (2) Using all three estimation methods, it was observed that the vegetation water demand in the areas designated as extremely important for ecological protection had increased over the past 30 years. Notably, the modified Penman formula method revealed the most pronounced increase, escalating from 1.212 billion cubic meters to 1.854 billion cubic meters. (3) A comparison of the three estimation methods revealed consistent trends in the estimated total vegetation ecological water demand every five years from 1990 to 2020. Similarly, the trends in vegetation ecological water demand within corresponding ecological protection grade areas estimated by each method were also consistent. This indicates the reasonableness of the ecological zoning method for estimating vegetation ecological water demand, providing a valuable reference for future estimations.