In order to meet the requirements of the optimization cycle time length and time scale precision in the optimization design of large capacity energy storage, a microgrid source and storage optimization method considering full-cycle chronological order characteristics is proposed. In this method, the data amount of the operation scenario is reduced from two dimensions by the clustering algorithm which considering the chronological order characteristics, and the obtained typical scenario can retain the full-cycle chronological order of the raw data. On this basis, a microgrid source and storage optimization model containing two time series is established. The sequencepreserving time series is used for the whole optimization cycle constraint to ensure the accuracy of model solving. The reduced time series is used for other constraints that do not require consideration of chronological order, so the complexity of the model can be reduced. The simulation results show that the proposed method is more accurate than other existing methods in the case of maintaining the same model complexity. The proposed method significantly improves the optimization accuracy of large capacity energy storage, and the optimization error of hydrogen energy storage capacity is reduced by more than 16%.