This article proposes a low-carbon economic optimization model for the power to gas carbon capture system (P2G-CCS), which takes into account the power to gas carbon capture system (P2G-CCS) mechanism and the power generation benefits of the collection and utilization of pressure energy in the natural gas transmission pipeline network. Firstly, a natural gas pressure energy power generation model is established based on the exergy analysis method, and a comprehensive energy system model for pressure energy power generation with P2G-CCS coupling technology is constructed. Secondly, the model is used to improve the system's capacity of wind rejection and carbon dioxide circulation, strengthen the electrical coupling and improve the power generation efficiency of the pressure energy power generation system. Finally, with the goal of optimizing daily operation economy, economic optimization scheduling analysis is conducted based on simulation examples to achieve low-carbon and economic performance of the system.