ABSTRACT The multi-microgrid integrated energy system offers multiple effective approaches to promote clean energy utilization as well as carbon emission reduction, etc. Combined with stepped carbon trading mechanism, it proposes a multi-microgrid (MMG) system with CCS-P2G integrated flexible operation method for optimal scheduling. Firstly, based on the microgrids’ “source-load” characteristic, electricity sharing between the source and load type microgrids can be achieved. Secondly, the CCS-P2G integrated flexible operation method is proposed, i.e. introducing HFC (Hydrogen Fuel Cell) and HES (Hydrogen Energy Storage) in P2G can enhance the utilization effect of hydrogen. Moreover, introducing carbon storage equipment in CCS, which can effectively solve the situation of unsynchronized operation times of CCS and P2G. Finally, introducing stepped carbon trading mechanism can be a further way of limiting carbon emission. Based on the above, MMG’s optimal dispatch model has established with objective of minimizing total operation cost by considering economic performance and carbon emission of the MMG system. Above optimal dispatch model is a mixed integer linear problem, which is solved using CPLEX solver. Simulation results show that electric energy interaction between source-type and load-type microgrids enhances renewable energy utilization rate. Compared to CCS-P2G cooperative operation method, the single-day carbon emissions and total operation cost of multi-microgrid system using CCS-P2G integrated flexible operation method are reduced by 37.02% and 6.80%, respectively. Meanwhile, when the stepped carbon trading mechanism was introduced, multi-microgrid system’s single-day carbon emissions is reduced to 5.40% compared to when normal carbon trading was considered, further constraining MMG’s carbon emissions.