Abstract: Enhancing the efficiency of territorial space utilization and promoting the coordinated development of urban, agricultural, and ecological space utilization are effective pathways to alleviate the tension between population and land resources and achieve sustainable regional development.The Yangtze River Economic Belt, as a core area of national strategy, still faces severe challenges such as the compression of ecological space and the misallocation of resources in its three major urban agglomerations.Scientifically evaluating the territorial spatial utilization efficiency and its coupled coordination characteristics of the three major urban agglomerations is of great significance for achieving regional sustainable development, optimizing resource allocation, and promoting the integration and high-quality development of the study area.This study took the period from 2000 to 2020 as the research period, and selected 70 prefecture-level cities in the three major urban agglomerations of the Yangtze River Economic Belt as the research objects.The Super-SBM model was constructed to measure the utilization efficiency of urban, agricultural, and ecological spaces.The exploratory spatial data analysis was used to parse the spatial association characteristics between subsystems.The coordinated development level of the utilization efficiency of the three types of spaces was quantified using the coupled coordination degree model. The results showed that: (1) There were significant differences in the spatial utilization efficiency of each subsystem in the three major urban agglomerations.The utilization efficiency of urban and agricultural spaces continued to rise, with the average annual growth rates of 16.3% and 5.9%, respectively.The utilization efficiency of ecological space generally declined, with the average efficiency value decreasing from 0.302 in 2000 to 0.251 in 2020.(2) The global spatial autocorrelation of each subsystem gradually increased, and there was a positive correlation between the utilization efficiency of urban-agricultural space and urban-ecological space, while there was a negative correlation between the utilization efficiency of agricultural-ecological space.The local spatial autocorrelation characteristics were mainly characterized by significant high-high and significant low-high clusters.(3) The coupled coordination of territorial spatial utilization efficiency in each region of the three major urban agglomerations showed an upward trend.The spatial distribution of the degree of coupled coordination showed the characteristic of "center-periphery" distribution.The number of coordinated areas increased from 9 to 16, but 54 cities were still in a state of disharmony (accounting for 77.1%).In the future, it is necessary to promote the coordinated development of the three major urban agglomerations, optimize the layout of urban, agricultural, and ecological spaces.It is also important to explore the spatial development strategies that meet the characteristics of different regions, and to promote the complementarity of advantages between regions to achieve sustainable high-quality development.