Abstract: Monitoring of ecological environment changes and providing suggestions for the future sustainable development of the Yellow River Delta hold significant practical importance under the background of ecological protection and high-quality development in this area. Taking the Yellow River Delta as the research area, five periods of Landsat images were selected as the data source. Based on the remote sensing ecological index (RSEI) model, the salinity index (SI) was used instead of the aridity index, then the air quality index (DI) was applied to construct the modified RSEI (MRSEI). Combined with landscape indices and the spatial auto-correlation analysis methods, the driving factors of spatiotemporal variation characteristics of the ecological quality of the Yellow River Delta were conducted quantitatively by geographic detectors. The results show that: (1) MRSEI was closer to the EI value compared with the traditional RSEI, and the evaluation results were more accurate to the actual situation, performing a reliable assessment for the ecological environment quality of the Yellow River Delta. (2) The ecological environment of the Yellow River Delta showed to be slightly deteriorated, with the mean ecological index decreasing from 0.53 to 0.51. Regions with poor ecological quality were mainly concentrated near the coastal tidal flats, while the better ecological quality were distributed in the southwestern and Yellow River coastal areas, gradually decreasing in ecological quality as they approach the coast. (3) The fragmentation degree of different levels of remote sensing ecological index patches kept rising, and the landscape pattern tended to become fragmented. (4) The spatial distribution of regional ecological index exhibited a significant spatial auto-correlation in each period, with local areas mainly characterized by high-high clustering and low-low clustering, which was consistent with the distributional changes of the MRSEI. (5) Land use presented the main factor affecting the spatial differentiation of regional ecological quality, and the interaction between the factors was manifested as mutual two-factor reinforcement.