In order to further reduce the carbon emissions of the integrated energy system (IES) and improve the energy utilization efficiency of the system, this paper designs an optimal scheduling strategy for the IES with low-carbon economy that takes demand response (DR) into account in the context of carbon trading. First, a laddered carbon trading mechanism was implemented to control the carbon emissions of IES. Second, a demand response model was constructed so that electricity, gas, and heat loads could respond flexibly. Finally, a low-carbon economy optimal dispatch model was built to achieve the purpose of minimizing the total operating cost of IES. The model is transformed into a linear mixed-integer programming problem via MATLAB and solved optimally using the CPLEX solver. The results of the case run show that the flexibility, economy, and low-carbon nature of IES can be significantly improved by combining demand response under the laddered carbon trading mechanisms.