Abstract: The relationship between integrated energy system, smart grid and energy internet was sorted out. The main characteristics and key technologies of energy internet were introduced. It was considered that integrated energy system was the concrete realization form of energy Internet at present stage. The composition and basic principle of integrated energy system were expounded. Based on the research results of related subjects and the practical experience of demonstration projects, the concept of essential demand for energy use was put forward. It was considered that the planning and construction of integrated energy system should focus on the essential demand for energy use of service parks and customers. The steps of regional energy demand analysis and the basic methods of decoupling integrated energy system were described. Suggestions for the development and construction of integrated energy system in the park were put forward.