Power to gas (P2G) technology converts electricity energy into natural gas, playing an important role in achieving a low-carbon economic dispatch in an integrated energy system. To solve the problem of underutilized oxygen in the P2G process and further reduce carbon emissions, a low-carbon integrated energy system that considers P2G oxygen-enriched improvement and combined solar energy utilization, handling carbon reduction from the following aspects is proposed. Firstly, the oxygen produced by P2G is mixed with CO₂ as an assistant combustion gas, and P2G utilizes captured CO₂ to produce natural gas for gas-fired units. Secondly, because the boiler efficiency is affected by the oxygen concentration, the optimal oxygen supply state for each period of the oxygen-consuming equipment is determined by a combined algorithm of genetic algorithm and Gurobi solver. Finally, the solar energy efficiency is improved by using mixed solar energy to reduce the use of fossil energy. By introducing oxygen-enriched and combined solar energy into the integrated energy system, a low-carbon economic operation model of the integrated energy system is constructed, and scenarios are set for comparison and verification. The simulation results show that the CO₂ emissions are reduced by 75.83% compared to the oxygen-enriched improvement before, and the total solar energy output is increased by 9.79% compared to the scenario without combined solar energy, indicating that the proposed model can effectively reduce carbon emissions and operating costs.