A low-carbon optimal operation model of an integrated energy system that takes demand response and double-layer power-to-gas conversion into account was proposed to increase system energy utilization and lower carbon emissions. Firstly, the optimization model of dual-layer electric-gas multi-energy complementary integrated energy system with high efficiency of hydrogen was established to study the advantages of hydrogen energy in many aspects. Secondly, the demand response model was modeled, which was divided into price type and alternative type according to the characteristics of flexible load. Thirdly, a stepped carbon trading mechanism was introduced to curb the carbon emissions of the system. Finally, taking Nanning Jiangnan industrial park as an example, the model was solved in CPLEX environment of MATLAB, and verified by scene comparison analysis. The results show that the model can fully mobilize the demand side to participate in the system optimization and achieve the effect of energy saving and emission reduction.