Abstract: Improving urban land use efficiency (ULUE) is crucial for achieving the optimal allocation of resources and promoting sustainable development. In this study, a super-efficient SBM-Undesirable model was established, based on the unexpected outputs such as carbon emission to assess the urban land use efficiency of 41 cities in the Yangtze River Delta urban agglomeration from 2010 to 2019. The spatial-temporal evolution characteristics, efficiency evolution and the decoupling relationship with economic development were explored. The results showed that：(1) Overall, the average ULUE in the Yangtze River Delta region was 0.71, indicating a low efficiency level. The ULUE showed a temporal pattern of increasing, then decreasing and finally increasing. The spatial deviations in ULUE demonstrated an increase first, followed by a decrease. (2) The spatial distribution of ULUE varied markedly, characterized by the lowest values in the center, and higher in the west, and lower in the east. Low degree of local agglomeration was also found. (3) Strategies to improve land use efficiency in the Yangtze River Delta region were mainly facilitated by a combination of catch-up efficiency (EC) and technological progress (TC). (4) From 2010 to 2019, the urban land use efficiency and economic growth in the Yangtze River Delta cities were dominated by a weak decoupling state, and the decoupling state was relatively satisfactory.