The unbalance between the renewable energy sources and user loads reduces the performance improvement of regional integrated energy systems (RIES), in which the multi-energy storage system with battery and heat tank is necessarily integrated. This paper aims to optimize the sites and capacities of multi-energy storage systems in the RIES. A RIES model including renewable wind power, power distribution network, district heating network, multi-energy stora. The unbalance between the renewable energy sources and user loads reduces the performance improvement of regional integrated energy systems (RIES), in which the multi-energy storage system with battery and heat tank is necessarily integrated. This paper aims to optimize the sites and capacities of multi-energy storage systems in the RIES. A RIES model including renewable wind power, power distribution network, district heating network, multi-energy storage system, and heat pump to convert electricity to heat is constructed. An optimization method combining a mixed-integer nonlinear programming optimization model is proposed to minimize the comprehensive cost of RIES. The second-order cone relaxation method performs convex relaxation of the power flow constraints, and the district heat network is operated under a constant-flow-variable-temperature strategy. The original optimization model is transformed into a mixed-integer second-order cone programming problem to solve. Three solution methods, including enumeration method, improved enumeration method and genetic algorithm, are employed to determine the optimum installation locations, and they are compared in computation time and efficiency. The results demonstrate that the distributed hybrid integration of electricity and thermal energy storages improves the RIES economy by collaborating the power and heat balances and reducing the purchased electricity from the grid. By integrating the hybrid storage system, the curtaile. ••A two-stage optimization model of multi-energy storage configuration is developed.••The sites and capacities of hybrid energy storages in power and thermal networks are optimized.••Three methods to determine the installation locations are compared.••The economics performances at different configuration strategies are compared.••Regional integrated energy systems (RIES)Multi-energy storage systemSiting optimizationCapacity optimizationCF-CT Constant-flow and constant-temperatureCF-VT Constant-flow and variable-temperatureDHN District heating networkESS Energy storage systemEES Electric energy storageRIES The depletion of fossil fuels and increasing environmental pollution have posed serious challenges to the global energy mix. With the proposed energy restructuring, the current status of global energy consumption relying on fossil fuels will gradually transform into a clean and green energy structure. The complementary structural forms of renewable energy sources such as wind, ocean, solar and geothermal energy combined with fossil energy sources are imperative to effectively mitigate the conflict between energy supply and demand and reduce carbon emissions. The proposal of the energy internet has provided new ideas for energy restructuring, in which regionally integrated energy system (RIES), also called smart energy system, is an important alternative scheme to integrate various forms of energy resources to produce various kinds of energy products of electricity, heating, cooling and gas. It realizes the unified coordination and planning of various energy resources for future renewable and sustainable energy solutions. But the uncertain renewable energy often doesn't match users' energy demands and decreases the energy utilization efficiency of RIES.As a key link of energy inputs and demands in the RIES, energy storage system (ESS) can effectively smooth the randomness of renewable energy, reduce the waste of wind and solar power, and decrease the installation of standb.