Land use function transition significantly impacts eco-environmental change. Understanding regional land use transitions is crucial for addressing eco-environmental issues. This study analyzes land use transition and eco-environmental quality in Dingxi City from 1990 to 2020 using remote sensing data and the "production-living-ecological space" perspective. Key findings include: (1) Ecological space increased by 519.54 km² , while production space decreased by 642.95 km² , and living space expanded by 123.93 km² . (2) Transition directions varied, with agriculture encroaching on ecological land from 1990 to 2000, and grassland and forest encroaching on agriculture from 2000 to 2020. (3) Eco-environmental quality exhibited a "U" trend, with higher quality in the south, lower in the middle, and medium in the north, influenced by mutual transitions between agriculture and forest land.