[Objective] This study aimed to clarify the spatiotemporal variation characteristics of vegetation water use efficiency（WUE） in Shaanxi Province and the individual impact mechanisms of the influencing factors.[Methods] Based on MODIS data products and data provided by the National Earth System Science Data Center, we analyzed the spatiotemporal variations of WUE across different vegetation types from 2001 to 2022 in Shaanxi Province. We also examined the response mechanisms of WUE to environmental and biological factors, including air temperature（T）, precipitation（P）, normalized difference vegetation index（NDVI）, potential evaporation（ET₀）, and vapor pressure deficit（VPD）. [Results] The multi-year average WUE of vegetation in Shaanxi Province was（2.1±0.4） g/（mm·m²）（calculated in C）, exhibiting a spatial pattern of higher values in the south and lower values in the north. The multiyear average WUE showed a non-significant increasing trend（p=0.46） with a single peaked pattern within the year. Significant differences in WUE were observed among different vegetation types（p＜0.05）, with the multiyear average WUE ranked as forest＞wetland＞cropland＞shrubland＞grassland. Forests showed a significant increasing trend in WUE from 2001 to 2022（p＜0.05）, while cropland and wetland demonstrated significant decreasing trends in WUE（p＜0.05）. Partial correlation analysis revealed that the relative importance of influencing factors on WUE ranked as T（33.24%）＞NDVI（30.80%）＞VPD（27.70%）＞ET₀（6.07%）＞P（2.08%）. [Conclusion] Vegetation WUE in Shaanxi Province showed a non-significant interannual increasing trend, and changes in vegetation WUE in the north-central and southern regions were mainly influenced by environmental factors and NDVI, respectively. The findings can provide references for the assessment and management of efficient water resource utilization during the ecological construction process in Shaanxi Province.