Promoting foreign trade development based on a circular economy is the key to dealing with the problems between the resource environment and economic growth. This paper first constructs a comprehensive evaluation index system of circular economy and foreign trade by taking 19 urban agglomerations in China as research objects. Secondly, the entropy value method is used to measure and analyze the circular economy development and foreign trade development of Chinese urban agglomerations from 2014 to 2021. Finally, the coupled coordination level of circular economy and foreign trade of Chinese urban agglomerations was measured using the coupled coordination degree model in physics, and the spatial and temporal evolution process of the synergistic development of circular economy and foreign trade of Chinese urban agglomerations was studied. The results show that the mean values of the coupling coordination degree of circular economy and foreign trade in the east and west regions of China from 2014 to 2021 are generally maintained above 0.85, and all tend to 0.95 equilibrium value, which is at a high coupling stage, indicating that there is an obvious interaction between the circular economy and foreign trade in China. This paper analyzes the spatial and temporal evolution of the coupling degree and coupling coordination degree of circular economy and foreign trade in Chinese urban agglomerations and provides a theoretical basis for governments at all levels to formulate policies and regulations on the synergistic development of circular economy and foreign trade in Chinese urban agglomerations.