Abstract: With the ecological environment problems being increasingly prominent and globalized, more and more attention is paid to environmental protection. Remote sensing technology is important in monitoring and evaluating ecological environment. In this study, based on the Landsat image data of 1992, 2000, 2008 and 2017, the remote sensing ecological index (RSEI) was constructed to monitor and evaluate the quality of ecological environment in Hangjin Banner, Inner Mongolia, aiming to provide a theoretical basis for local ecological environment protection. The results showed that from 1992 to 2017, the quality of ecological environment in Hangjin Banner was generally poor, with RESI grades of poor and inferior. The mean value of RESI increased from 0.31 (1992) to 0.37 (2008) and then decreased to 0.30 (2017). During the period, the change range was mainly from one grade to the next. In terms of spatial distribution, the regions with poor ecological environment quality were mainly in the desert plains of the central and western regions, that with good ecological quality mainly along the Yellow River and in the southeast, and that with large fluctuation of ecological quality grade mainly in the desert edge along the Yellow River and in the hilly and gully regions in the east. During the research period, the center of gravity of each ecological grade in Hangjin Banner substantially shifted, with spatiotemporal fluctuations. Our results suggest that ecological environment of Hangjin Banner was fragile and unstable. Ecological construction can promote the quality of ecological environment, but resources and land use should also be reasonably allocated.