Abstract: Integrated energy system (IES) and shared energy storage offer significant benefits for achieving the "dual carbon" goals. To address the conflicts of interest among multiple decision-makers within IES and the lack of energy storage participation in optimization, an optimal scheduling model for IES with shared energy storage based on Stackelberg game theory is proposed. Firstly, the framework of the user-side micro-energy system and the role of each decision-making body in the system are described. Secondly, optimization operation models for the microgrid operator (MGO), shared energy storage operator (SESO), and user aggregator (UA) are established. A Stackelberg game model is constructed for IES with shared energy storage, where the MGO acts as the leader and the UA as the follower. The existence and uniqueness of the Stackelberg equilibrium solution are demonstrated. Finally, case studies validate the effectiveness of the proposed optimal scheduling model. Experimental results show that the model significantly enhances the flexibility of electricity and heat regulation on the user side, provides decision-making strategies for electricity and heat pricing for the MGO, and achieves a win-win outcome for both SESO and UA in terms of revenue. This research offers a feasible solution for optimizing the operation of IES with shared energy storage.