Abstract: Based on the monthly meteorological observation data from 38 meteorological stations in Xizang from 1981 to 2023, as well as the indices of atmospheric circulation, sunspots and sea surface temperature (SST), the spatiotemporal variation characteristics and influencing factors of the vapor pressure deficit (VPD) during the vegetation growing season in Xizang over the past 43 years were analyzed by Pearson correlation coefficient, linear tendency estimation, Mann-Kendall method and stepwise regression method. The results show that: (1) Spatially, the multi-year average growing season VPD is bounded approximately by 95°E, with values generally increasing from east to west of 95°E, and decreasing radially outward from Baxoi as the center east of 95°E. VPD decreased (increased) with the increase (decrease) of altitude above (below) 3300 m. (2) Over the past 43 years, the average growing season VPD in Xizang showed a significant increasing trend, with a rate of 0.028 kPa/decade, mainly in August and September. The mutation occurred in 2005. Among all stations, 79% of the meteorological stations showed a significant increasing trend in VPD. (3) VPD was lower in the 1980s and 1990s, especially in the 1990s. It was slightly higher in the 2000s and significantly higher in the 2010s. (4) Temperature warming was the dominant meteorological factor for the increase in growing season VPD, and the increase of the Western Pacific subtropical high area index and the Indian Ocean warm pool area index were the dominant circulation factor and the dominant SST factor, respectively. In addition, sunspots were significantly negatively correlated with VPD.