Abstract: Regarding the intrinsic features of emergency materials, i.e., fixed variety, strong randomness of the in-storage and the out-storage, and being held for multiple periods of time but not regularly, we propose an optimal inventory model for single and multiple periods. The model analyzes the critical storage point at an optimal moment, which determines the order quality. Theoretical derivation and numerical examples illustrate the economy and efficiency of the model. The result supplies a theoretical basis for warehouse management of reserved emergency materials.