[Objective] The current level of ecological environmental change in the Yuanmou dry-hot valley from 2000 to 2020 was determined, and the dynamic monitoring and driving force of the regional ecology were analyzed in order to provide a theoretical basis for ecological environmental protection and sustainable development of the dry-hot valley. [Methods] Three Landsat TM/OIL image datasets were selected to calculate the greenness (NDVI), humidity (WET), dryness (NDBSI), and heat (LST) indexes to construct the remote sensing ecological index (RSEI) evaluation system. The ecological environmental factors affecting the region were quantified and analyzed by geographic detector. [Results] ① The mean values of RSEI in the Yuanmou dry-hot valley in 2000, 2010 and 2020 were 0.628, 0.609, and 0.684, respectively, showing a trend of initially decreasing and then increasing. ② During the 20-year study period, the area of ecological environmental improvement accounted for 29.58% of the total area, mainly located on both sides of the river valley. The area of ecological deterioration accounted for 21.45% of the total area, and was mainly scattered around agricultural areas and residential areas. ③ The driving force analysis of 10 factors affecting RSEI in the Yuanmou dry-hot valley showed that NDVI and land use had the strongest explanatory power for the spatial differentiation characteristics of RSEI. [Conclusion] The interaction results of multiple factors showed that the ecological environment of the Yuanmou dry-hot valley was the result of multiple factors, and all factors produced synergistic enhancement effects under the interaction. NDVI and land use were the main driving factors of eco-environmental quality in the study area. Therefore, in the exploration of Yuanmou ecological environmental restoration and protection, we should rationally plan and use land resources, and implement vegetation protection and restoration policies and measures.