A two-stage low-carbon optimization scheduling model for PIES based on multi energy flow coupling and carbon electricity market synergy is established. First, the park-level integrated energy system（PIES）multi energy flow virtual carbon flow transmission mechanism based on the unified energy bus structure is studied, the concept of energy bus“carbon flow density”and the principle of carbon emission conservation within the energy storage and scheduling cycle are introduced, and the PIES multi energy supply, consumption carbon emission accounting system is designed. Second, the carbon flow density of the regional power grid is used to calculate the carbon emissions, and PIES economic dispatching is one-stage. A two-stage optimization model of low-carbon DR optimal scheduling with the signal of stepped time-sharing carbon price is constructed to reduce the total carbon emissions by using users’willingness, and load side regulation capacity. Finally, a typical PIES is used to analyze numerical example. The results show that the proposed optimization model can make timely response according to the carbon flow density trend of the regional power grid, and user side DR to minimize its own carbon emissions and achieve the goal of deep emission reduction.