In a certain area, the regional integrated energy system integrates coal, oil, natural gas, electrical energy, thermal energy, hydrogen energy, mechanical energy and other energy sources to achieve coordinated planning, optimized operation, collaborative management, and multi-energy complementarity. The ultimate goal of the regional integrated energy system is to improve the efficiency of energy comprehensive utilization. Firstly, the key elements such as electricity, gas, cold and heat in the regional integrated energy system are modeled and the mutual coupling techniques are studied. Then the comprehensive evaluation indicators and evaluation methods for the regional integrated energy system are established. The objectives of optimization includes energy supply reliability, energy quality, economic benefits, energy conservation, emission reduction, grid friendliness, program adaptability, and so on. Meanwhile, the planning and design of the system architecture is researched, determining the optimal energy types and energy ratios in the regional integrated energy systems. Based on the above analyses, multi-objective optimization of the regional integrated energy system are conducted using nonlinear optimization method. The obtained results are evaluated according to the evaluation indicators from the technical and economic aspects.