Abstract: Balancing the relationship between emission reduction and development is crucial for the Yangtze River Delta urban agglomeration to achieve the "dual carbon" goal and economic transformation and upgrading. Based on the constructed evaluation index system of carbon emission reduction and high-quality economic development, this study analyzed the spatial-temporal evolution characteristics and the driving factors of the coupling coordination degree between carbon emission reduction and high-quality economic development from 2006 to 2021. The coupling coordination degree, spatial autocorrelation model and geographic detector were used. The results showed that:（1）the comprehensive level of carbon emission reduction and high-quality economic development in the urban agglomeration showed an increasing trend during the study period, but the latter had obvious fluctuations.（2）the coordination between carbon emission reduction and high-quality economic development was good, but the degree was not high, and there was a large gap between the coordination degree of the internal regions. In terms of coordination type, the reluctant coordination level was dominant, and the general dissonance level was relatively small.（3）the coupling coordination degree had significant spatial differentiation and spatial agglomeration.（4）the coordination degree of the urban agglomeration  was mainly affected by five factors, including green travel, urban greening, structural adjustment, technological innovation and public service supply. Regionally, due to the different natural and economic environments of Jiangsu, Zhejiang, Anhui and Shanghai,  differences in the factors driving the coordination degree were found.