Clarifying the spatiotemporal patterns and driving mechanisms of vegetation growth and sensitivity is critical for assessing ecosystem stability and formulating conservation strategies. Taking Northwest China (NWC)-the core of global mid-latitude arid regions and China's "Northern Ecological Security Barrier"-as the study area, we analyzed vegetation growth (via EVI) and sensitivity (via VSI) dynamics, and their climatic drivers (temperature, precipitation, and solar radiation) (2000-2022) using a novel EVI-VSI synergetic framework, combined with growing-season EVI data, China's national climate/vegetation zoning, and statistical methods (ANOVA, Mann-Kendall trend test, 11-year moving window). The results show that: 1) EVI showed significant zonal differences (all P < 0.001): under climate zoning, mean EVI followed "humid (0.46 +/- 0.06) > semi-humid (0.31 +/- 0.08) > semi-arid/arid (0.21-0.22)"; VSI (regional mean: 47.10 +/- 20.01) had no zonal differences (P > 0.05), with low spatial overlap between high-EVI and high-VSI areas. 2) EVI increased significantly (0.0021 a(-1), P < 0.01), with 88.21% of the region improving (highest in humid zones: 99.16%); VSI decreased non-significantly (-0.021 a(-1), P > 0.05), with wetlands showing a lower decline (45.56%) due to human disturbance (grazing, tourism). 3) climatic drivers exhibited distinct zoning differences, with a post-2010 trend of "weakened temperature dominance, enhanced radiation dominance": semi-arid zones saw the proportion of radiation-dominated areas undergo a marked surge across the study period, rising from its lowest point (9.51% in 2007) to its peak (46.35% in 2017), making it the dominant driver; arid zones had 34.90% precipitation-dominated areas (significantly higher than humid zones' 12.86%); humid/semi-humid zones showed increased precipitation/radiation sensitivity but decreased temperature sensitivity. This study innovatively reveals the "radiation substitution for temperature" driving transition of vegetation sensitivity in arid/semi-arid regions, and provides scientific support for precise ecosystem conservation and climate adaptation in NWC, as well as a reference for vegetation management in global mid-latitude arid zones (e.g., Central Asia, North American Great Plains).