Abstract: With the gradual opening of the carbon markets and the distributed generation trading markets, the economic incentive trading market mechanism has become an effective way to promote the carbon emission reduction for the microgrids (MG). This paper proposes an electricity-carbon coupling trading mechanism based on the carbon flow tracing for a multi-microgrid (MMG) system. Firstly, the carbon emission model of each of the components in the MG and the carbon flow tracing model of the MMG system are established. Consider-ing the influence of the carbon emission fluctuation of the unit electric energy caused by the charging/discharging behaviors of the energy storage equipment on the carbon flow tracing results, an accompanying carbon emission density (ACED) concept is proposed, and the carbon flow index calculation matrix considering the charging/discharging characteristics of the energy storage equipment is derived. Besides, based on the carbon flow tracing results, a dynamic carbon emission factor-driven low-carbon demand response model is estab-lished for the users inside the MG. On this basis, an electricity-carbon coupling trading mechanism of the MMG system coordinated by the distribution network operator (DNO) is proposed to realize the optimal scheduling of the MMG system under the background of electricity-carbon coupling trading in order to encourage each MG to actively participate in the trading. Simulation results show that the electricity-carbon coupling transaction mechanism plays the role of facilitating the flexible operation of the MG and improving its eco-nomic benefits. The consideration of the carbon emission flow in the operation process enables the users to actively participate in low-carbon demand response, which further promotes the environmental benefits and effective carbon emission reduction of the MMG sys-tem.