Abstract: The coordinated development of two-way FDI is the key to building a new development pattern of "double-cycle", and is also an important focus point to promote carbon sequestration and emission reduction to realize the goal of "double-carbon". After clarifying the influence mechanism of the coordinated development of two-way FDI on carbon balance, this paper empirically tested the impact and mechanism of the coordinated development of two-way FDI on carbon balance, based on the panel data of 11 provinces of the Yangtze River Economic Belt from 2008 to 2021. The dynamic spatial Durbin model and the mediation effect model were used in this study. The results showed that: (1) The average value of coordinated development level of two-way FDI showed a fluctuating upward trend, and the spatial pattern was characterized by "upper reaches<middle reaches< lower reaches"; The average value of carbon balance ratio showed a fluctuating downward trend, and the spatial pattern was characterized by "upper reaches>middle reaches> lower reaches". (2) The impact of the coordinated development of two-way FDI on carbon balance presented a "U" shape and had a significant spatial spillover effect in the Yangtze River Economic Belt. (3) There was a significant mediating effect of technological progress and industrial structure upgrading in the coordinated development of two-way FDI affecting the carbon balance. (4) There existed regional heterogeneity in the impact of the coordinated development of two-way FDI on the carbon balance in the Yangtze River Economic Belt. The size of the inflection point of the "U" curve was characterized by "Upper reaches > Middle reaches > Lower reaches". Therefore, there existed room offurther promoting the carbon balance, strengthening a high-quality opening and of a synergistic regional development in a long-term.