Abstract: The Flexible application of hydrogen and methane, generated through the two stages of electrolytic water and methanation in the power to gas (P2G) system, can promote the capability of the integrated energy system (IES) in absorbing surplus renewable energy. The traditional P2G system only considers methane as the fuel for the gas units, neglecting to fully exploit the high electrolysis rate of hydrogen. Consequently, this leads to an increase in the number of energy cascade conversions and a subsequent rise in energy loss. In this paper, we apply the hydrogen and methane coupled hydrogen injection into gas grid (HIGG) technology, produced in two stages of the P2G system, to promote the absorption of renewable energy in IES. Based on the concept of energy hub, the economic optimal scheduling of IES system is transformed into a mixed integer programming problem. The simulation analysis of two scenarios demonstrate that compared with the traditional P2G system which only employs methane, the application of P2G coupled with HIGG technology in the IES system can reduce the number of energy cascade conversions and cost input, significantly improving the economic viability and environmental sustainability.