Abstract: The increasing penetration of renewable energy presents significant challenges in optimizing thermal coal stockpiling for both daily thermoelectric power production and emergency response to accidental events, which are crucial for maintaining the economic efficiency and stability of the new power system. This research addresses these challenges by incorporating the coupling characteristics of wind and solar power generation into the procurement and reserve decision-making process for regional thermal coal stockpile hub. To generate representative scenarios, a joint interval segmentation approach based on clustering of wind and solar power output data is proposed to identify characterized periods. A dynamic programming model is developed to optimize both safety and economic efficiency through dual-purpose reserves. Empirical results demonstrate the validity of the proposed method. Additionally, scene examinations validate the robustness and economic efficiency of the dual-purpose reserve structure. This study offers theoretical support and practical guidance for optimizing coal reserves in the evolving power system.