Spare parts warehouse management is a challenging issue due to the volume and variety of spare parts. Most often, it is observed that certain spare parts are used together for various maintenance activities of equipment. Group and frequent use of spare parts, creates dependency. Sometimes the entire maintenance work cannot be accomplished Due to the shortage of a single spare part in the group. Also, due to the random demand and deficiencies in the system, the role of substituting items cannot be ignored. On the other hand, high cost of spare parts and budget constraints, challenges decision making. In this study, a model for the total cost of spare parts inventory is provided considering the dependency and substituting features between spare parts and potential demand by the Poisson distribution.