As the proportion of new energy sources in the power system continues to increase, the demand for flexibility resources within the system is progressively rising. Flexibility resources such as pumped hydro storage and demand response have been widely applied in power system dispatching. To further enhance the system"s low-carbon nature and flexibility, Grid-connection of wind power and photovoltaic and fire power and pomped storage dispatch scheme combined with demand response, is proposed. First, the joint scheduling mechanisms of pumped hydro storage, carbon capture, and demand response are analyzed. By employing peak shaving and valley filling strategies, the complementary advantages of different resources are fully utilized during periods of high and low net load, achieving a smoothing of the load curve. Secondly, based on flexibility constraints related to transmission line capacities, a two-stage scheduling model is constructed: the first stage optimizes load curve fluctuations by minimizing the net load difference, and the second stage formulates a dispatch plan aimed at minimizing system operating costs while considering the system’s economic performance, flexibility, and low-carbon objectives. Finally, simulations conducted on an improved IEEE-30 node system demonstrate that the proposed scheme effectively enhances the absorption capacity of wind and solar energy, reduces system operating costs and carbon emissions, and provides new insights and technical support for the dispatching of future low-carbon power systems. This approach offers significant references for energy structure transformation and green low-carbon development.