In response to the difficulties in carbon trading cost-sharing and the insufficient motivation for emission reduction in the integrated energy system under the dual-carbon targets, a low-carbon economic scheduling strategy based on a multi-principal carbon trading cost-sharing mechanism is proposed. Firstly, a multi-principal carbon trading cost-sharing model is designed, considering the flexible adjustment and response mechanisms on both the source and load sides. Secondly, a master-slave game low-carbon economic dispatch model is constructed, with the energy seller as the leader and the energy supplier and load aggregator as followers. The leader formulates dynamic time-sharing carbon prices to guide the energy supplier in optimizing equipment output strategies and the load aggregator in adjusting energy consumption strategies. Finally, several scenarios are compared and analyzed through simulation experiments. Results demonstrate that, compared with the average of three mechanisms where a single subject bears the carbon trading cost, the proposed multi-principal carbon trading cost sharing mechanism increases the system's overall total benefit by 3.71%, reduces total costs by 11.97%, cuts carbon trading costs by 21.06%, and decreases total carbon emissions by 19%. This model effectively realizes the sharing of carbon trading costs among multiple subjects, promotes cooperation in emission reduction among all parties, and achieves a win-win situation in economic and environmental benefits.