Abstract: This study uses Landsat TM/OLI remote sensing images from 2000, 2005, 2010, 2015, and 2020 as the main data source to construct an improved karst remote sensing ecological index. The temporal and spatial changes of the ecological environment quality in Qujing City from 2000 to 2020 were analyzed by combining the Sen slope estimation and the Mann–Kendall trend test. At the same time, the optimal parameter geographic detector model was used to optimize the zoning effect of spatial data to study the impact of different factors on the spatial heterogeneity of ecological environment quality. The results show that from 2000 to 2020, the overall ecological environment quality in Qujing City has improved, with significant spatial heterogeneity. In terms of space, it presents a distribution pattern of "low in the northwest and high in the southeast", and the area of "excellent" and "good" levels has gradually increased. According to the trend analysis of Sen slope and MK test, the area of improved ecological environment quality accounts for more than 60%, but some areas still show degradation. The results of the optimal parameter geodetector model show that the ecological environment quality is affected by multiple factors, among which NPP, land use type, DEM and temperature have significant effects, and the interaction of various driving factors further deepens the impact on ecological quality. The research results can provide a methodological reference for remote sensing evaluation of ecological environment quality in karst areas, which will help promote ecological environment protection and regional social and economic sustainable development in karst areas.