Integrated energy supply system of pelagic clustering islands (IESS-PCI) can meet the load demand of the main island more effectively. It strengthens the sense of cooperation between the islands and improves the stability of renewable power supply. It provides a more reliable mode of operation for pelagic clustering islands. The operation mode of IESS is introduced and the preliminary planning of IESS's production capacity and transport capacity is achieved in this paper. Combining the geographical conditions and natural data, the installation capacity of wind turbines, photovoltaic panels and wave power generation devices on satellite island is optimized by the algorithm of multi-objective particle swarm optimization (MOPSO). The model of the transportation is transformed into the specific problem of linear programming to determine the optimal capacity of the battery and the storage tank on the transport vessel. Taking Paracel Islands of China for an example proves the feasibility of IESS and the rationality of the whole system.