Abstract: This study utilized Landsat remote sensing images from 2013 to 2022, introduced the Mountain Vegetation index (NDMVl) and Composite Salinity Index (CSl) to construct an improved Ecological Environment Evaluation Model (ERSEl). Geographic detectors, Sen-MKtrend tests, and Hurst indices were employed to dynamically monitor and evaluate the ecological environment of Sunan County, providing scientific support for the protection of the Qilian Mountains and the county's development. The study found: ①From 2013 to 2022, the ecological environment of Sunan County has shown a stable and positive trend with minimal changes, experiencing a "rise-decline-rise" process.②Minghua Township and the northern part of Dahe Township have poorer ecological environments, with the lowest ERSEl values, while the ecological environment in Kangle Town and Matie Township within the Qilian Mountains Nature Reserve is better with the highest ERSEl reaching 0.7.③The ecological environment of Sunan County is generally stable, with over 90% stability. Improvement areas are scattered, primarily located in the southwestern and southeastern farming regions of Minghua Township and the northeastern part of DaheTownship, accounting for 6.61%.④Natural conditions and socio-economic factors have a significant combined impact on ERSEl, with g-values of 0.60 and 0.62, respectively. Precipitation, temperature, cropland protection, and livestock numbers are strongly related to ERSEl. The interaction effects of different factors significantly influence ERSEl, particularly the interaction between cropland protection area and ecological protection red lines, as well as temperature and precipitation, which are crucial for improving ERSEl values.⑤Nearly 70% of Sunan County's land is ecologically sustainable, and the ecologicalenvironment is expected to continue its current improvement trend in the future.