Abstract: Aiming at the environmental pollution caused by conventional fossil fuel units in solving islands energy supply, this paper aims at 100% renewable energy generation to meet the load demand and focus on the optimal sizing of island microgrid clusters based on 100% green energy power supply. Firstly, the island microgrid clusters composed of different functional types of microgrid was constructed, and the operation rule of 100% green energy power supply and the corresponding coordinated control strategy were formulated. Then, an operating cost dynamic optimization strategy of aiming at minimizing the operating cost of energy storage system was designed according to the operating characteristics of battery and pumped-storage station. Finally, NSGA-Ⅱ algorithm was used to solve the capacity optimal sizing model in different scenarios, and the influence of uncertainty of the renewable energy generation and load fluctuation on the optimal sizing results was analyzed. The results show that the proposed island microgrid clusters optimal sizing model can realize the target of 100% green energy power supply with meeting the economic and reliability requirements, which provides an engineering reference for the development of eco-friendly island microgrid.