Regional integrated energy system(RIES) is a kind of comprehensive energy production form which integrates multiple energy resources, and has the characteristics of high energy efficiency, multi energy complementarity, and low carbon emissions. The research on the optimal allocation method of RIES is helpful to energy conservation and emission reduction, ensure regional energy security and promote the substantial consumption of renewable energy. In this paper, a regional integrated energy system optimal allocation model with topology planning was established. The basic idea is to use distributed energy station as the basic energy supply unit, and connect the energy systems distributed in different regions by introducing the selection and capacity configuration constraints of power lines and heat transmission pipelines; then, taking into account the influence of factors such as pipeline loss, capacity limit, and voltage amplitude, a mixed integer linear programming model for multi region energy interconnection system was constructed with the objective of economic optimization. The objective function includes investment cost, replacement cost and equipment residual income. The test results show the planning model can effectively reduce the installation capacity of redundant equipment, improve the economy of the planning scheme and the energy efficiency of the system, which has a certain reference value for the planning and construction of regional integrated energy system.