Under the dual-carbon target, the power industry needs to promote the reform of the power trading system to reduce carbon emissions, and it is very important to build a carbon market, green certificate market and electricity market coupling trading mechanism. This paper proposes a System dynamics carbon-green card-electricity market transaction coupling mechanism to construct a new low-carbon trading system from the macro-modeling level. Firstly, the carbon trading mechanism based on baseline method and the green certificate trading mechanism considering historical completion degree data are modeled respectively. Then, from the perspective of System dynamics theory, a modeling method of the carbon-green certificate-electricity market coupling trading mechanism is proposed. Finally, the proposed mechanism is simulated using data from Fujian, China, and the results prove the effectiveness of the proposed mechanism.