Shared energy storage is an effective measure to improve the efficiency of energy storage and play the synergistic advantages of micro-energy grid clusters, however, most of the existing studies have simplified the energy transmission channel between shared energy storage and micro-energy network clusters into a bus structure, which has problems such as 'fixed capacity’ but not 'siting’, insufficient utilisation of shared energy storage after configuration, and so on. There are problems such as only 'capacity-setting’ but not 'siting’ and insufficient utilisation of shared energy storage after configuration. In this context, a two-layer optimal configuration model of shared energy storage for micro-energy grid clusters is established, taking into account the carrying capacity of the power grid. Firstly, a two-layer configuration model of shared energy storage for micro-energy grid clusters is established: the upper model takes the minimisation of the operating cost of the power grid and the shared energy storage planning as the goal, and optimises the decision-making of the location and capacity of the shared energy storage by taking into account the carrying capacity of the power grid; the lower model takes the minimisation of the operating cost of the micro-energy grid as the goal, and optimises the solution to the micro-energy grid operation problem. Secondly, the lower-layer model is converted into the constraints of the upper-layer model based on the KKT condition, and the two-layer optimal allocation model is converted into a single-layer optimisation problem. Finally, a comparative analysis is conducted using a test case containing three micro-energy grids. The results show that the proposed model can fully consider the carrying capacity of the grid and obtain a shared energy storage siting and capacity-setting scheme with better economic benefits and shorter payback period.