The integrated energy system provides strong support for energy transition and the realization of the “double carbon” goal through the synergistic optimization and efficient operation of multiple energies, but it covers a variety of energy forms, such as electricity, heat, gas, etc. The nonlinear coupling relationship between different energy systems and cross-domain parameter interactions greatly increase the difficulty of its dynamic modeling. Therefore, this paper adopts a modular modeling approach, establishes a multidomain unified mathematical model of the integrated energy system, and analyzes the dynamic response between different energy flows when the load of the integrated energy system changes, and the results show that: the multidomain unified modeling approach proposed in this paper has a good effect on describing the dynamic characteristics of the network of the integrated energy system, as well as the dynamic response between different energy flows, and the results can provide theoretical and technical support for the control and scheduling of integrated energy systems, optimization of multi-energy synergies, efficient operation, high-proportion renewable energy consumption, and scientific management.