Land-use change is a consequence of human activities and climate change. It is heavily influenced by population migration, which further changes eco-environment. Therefore, investigating the impact of population migration on land-use change and its eco-environment implications can provide valuable theoretical support and reference for the rational land resource planning and utilization, as well as the sustainable development of the regional eco-environment and economy. In this study, we analyze the characteristics of regional land-use patterns and their changes in Liangshan Prefecture, Sichuan Province, which has experienced significant migration over the past decades. Using long-term and high-resolution land-use data, we examine the variations in eco-environment quality within the context of migration. The findings reveal the following: (1) From 2000 to 2020, the utilization pattern and intensity of land resources in Liangshan Prefecture underwent significant alterations due to population migration. The most prominent transformations were observed in the areas of cropland, grassland, forest, and impervious surfaces. In counties and cities such as Xichang, Mianning, and Dechang, which experienced a substantial population influx, there was a notable increase in the number of cropland and construction land required for human life and sustenance. In contrast, in regions like Xide, Zhaojue, and Meigu, where a sizeable number of people relocated, the decrease in human activity intensity created conditions conducive to the restoration and rehabilitation of ecological land, leading to a distinct expansion in ecological land area. (2) Influenced by variables such as land use patterns, topographical conditions, and population dispersion, the spatial distribution of overall eco-environment quality in Liangshan Prefecture exhibited a west-high, east-low, and north-high, south-low trend. Over the period from 2000 to 2020, a slight decline in quality was observed, yet the overall stability was maintained. (3) The eco-environment quality improvements were predominantly observed in the eastern region of the state, while declines were primarily centered in the western region. A clear correlation existed between variations in eco-environment quality and regional migration activities. Notably, the conversion of cropland and impervious induced by migrant inflows contributed to 87.97% of the overall eco-environment quality degradation. Concurrently, population migration has spurred the implementation of ecological projects, leading to the addition of 775.84 km² of ecological land within Liangshan Prefecture. Our study highlights the significant impacts of population migration on land-use change and eco-environment quality in Liangshan Prefecture. The findings emphasize the need for effective land resource management and ecological protection measures to mitigate potential ecological risks associated with ongoing migration trends. Furthermore, the investigation of regional land-use changes and eco-environment quality provides valuable insights for sustainable development strategies and decision-making processes in Liangshan Prefecture and other similar regions.