Developing a user-side integrated energy system holds significant importance in advancing China's energy revolution. However, the complexity of such systems, consisting of numerous interconnected forms of energy, presents a daunting challenge for optimal planning. This manuscript proposes a stochastic mixed integer linear programming model to tackle this challenge and plan user-side integrated energy systems effectively. The model's objective function aims to minimize investment costs in the system's surge phase. Separate operating constraint models are established for the electrical, heat, cooling, and gas equipment involved. Commercial solving software is employed to obtain optimized solutions based on typical scenarios. The proposed model offers the best planning scenario, including equipment type and capacity, and operational strategies. The model is then applied to the planning of user-side integrated energy systems, verifying the effectiveness of the model and its solution methodology.