This study calculates the carbon emission performance of 277 Chinese cities from 2006 to 2020 with the help of an SBM-DEA model, displays its evolution characteristics using the ArcGIS platform, and empirically tests and analyzes the local and spatial spillover effects of economic transformation on carbon emission performance using the spatial Durbin model. The results showed that： ① The carbon emission performance level of Chinese cities was generally high, but the trend of decline was obvious, and the distribution showed the characteristics of low-level agglomeration from equilibrium distribution to U-shaped transformation. ② At the current stage, the local promoting effect of economic transformation on the improvement of carbon emission performance has not been fully revealed. The marketization, globalization, and fiscal decentralization of local urban economic transformation significantly improved the carbon emission performance of local cities, but the decentralization of administrative categories, the intensity of environmental regulation, and the level of green technology innovation inhibited the improvement of carbon emission performance. ③ Carbon emission performance was spatially dependent. The globalization level of economic transformation, environmental regulation intensity, green technology innovation level, and improvement of carbon emission performance of neighboring cities had a positive spillover effect on local carbon emission performance, while the decentralization level of administrative categories had a negative spillover effect. Clarifying the level and distribution of urban carbon emission performance and explaining it from the perspective of economic transformation is of great practical significance for promoting the realization of the "double carbon" goal in China and other countries.