Most of the existing planning strategies for the electricity gas-heat-integrated energy system are realized by cutting or transferring the load, and the influence of the dynamic coupling process is not considered. Therefore, the scheduling is not flexible enough. Under the background, a two-layer optimal scheduling model that considers the Dynamic Energy Conversion (DEC) energy storage and loads collaborative optimization strategy is proposed in this paper. In the upper layer, the dynamic conversion of energy flow is considered and the whole life cycle impact of the electric facilities, such as batteries, super-capacitors, and electricity to gas, is also concerned. Then the DEC load model is introduced. For the lower layer, based on the configuration of energy storage of the upper layer, an optimal scheduling model of an integrated energy system is established with the operating cost and net loss as the objective function. The scheduling results will be fed back to the upper layer. And then the DEC load can participate in the secondary scheduling and the flexibility of scheduling can be enhanced. In addition, the Second Order Oscillatory Particle Swarm Optimization algorithm is adopted to calculate the solution of the upper model, while the lower model utilizes the ε-constraint method to solve the nonlinear equations. Finally, an Integrated Energy System comprising the modified IEEE 39 Panel Point Power System, the Belgian 20 Panel Points Natural Gas System, and the 6 Panel Points Heat System is analyzed as an example. Four operation scenarios are discussed from the perspectives of economy, reliability, and flexibility to verify the rationality and superiority of the proposed model and algorithm.