Abstract: To support the national strategy of "Ecological Protection and High-Quality Development in the Yellow River Basin", this study selects eight indicators, i.e. mean annual temperature, annual precipitation, elevation, slope gradient, slope aspect, vegetation index, land use (natural resource) type and soil type, and establishes a comprehensive evaluation system to assess the ecological vulnerability in Lanzhou Basin during 1990-2020. With principal component analysis (PCA), the ecological vulnerability of the region over this period is analyzed. The results show that the comprehensive ecological vulnerability indices for 1990, 2000, 2015, and 2020 are 0.93, 1.06, 1.04, and 0.90, respectively, indicating a generally low level of ecological quality with a trend of initial deterioration followed by subsequent improvement. Spatially, the ecological vulnerability consistently exhibited a pattern of "high in the north and low in the south" across all four periods. During 1990-2000, ecological conditions generally worsened in the northern low mountain and hilly areas, while significant improvement was observed along the Yellow River. In the central area, vulnerability evolved from light and moderate to severe levels, whereas a notable recovery occurred in the southern Xinglong Mountain area. No significant changes were detected during 2000-2010. However, a marked overall ecological improvement was evident from 2010 to 2020, with ecological vulnerability in Yuzhong Basin being generally lower than that in 2010. The primary influencing factors for ecological vulnerability include elevation, slope gradient, precipitation, vegetation, natural resource type, and soil type. These findings on ecological vulnerability dynamics may provide data support for the integrated management of natural resources, theoretical research, and ecological monitoring within territorial spaces.