Abstract: Under the carbon peaking and carbon neutrality goals, the connection among wind energy, solar energy and hydrogen energy is increasingly close, and reasonable capacity allocation is an effective way to ensure the stable operation of the electro-hydrogen coupling system. A long-term capacity optimization method was proposed for an independent microgrid with combined operation of wind-photo-hydrogen storage-ultracapacitors. By considering the dynamic efficiency of hydrogen storage system, the working interval of hydrogen production and hydrogen consumption equipment was optimized, and a reasonable control strategy of microgrid operation was developed. In order to reflect the real long-term trend of the meteorological factors, the long-term forecast of typical days was carried out based on the Pearson correlation coefficient and grey rolling prediction method, and the optimized input samples were obtained. A capacity optimization model was established to optimize the economy, reliability and low carbon of microgrid, a multi-objective particle swarm optimization algorithm (IMOPSO) with nonlinear dynamic weight was used to solve the Pareto set, and the membership analysis method was introduced to give the optimal planning scheme.Simulation results show that, compared with the current research results, the proposed method benefits from the analysis of dynamic characteristics of hydrogen storage units and the improvement of input samples, and can give better configuration results.