Inventory management requires high investment in the company, including spare parts companies. Currently, inventory problems at spare-parts Company that is too many types of components (spare parts), some components (spare parts) there are overstock, some others stock-out, and planning the purchasing of components (spare parts) still quite often using intuition. The purpose of this study is to improve inventory management performance solve the inventory problems at Indonesia spare-part company, so the company can establish an economical supply budget by setting safety stock, minimum stock, maximum stock, and order quantities of each components (spare parts) required to Obtain the inventory cost saving. This study was initiated through the stages of ABC analysis to determine the grade of material on each item, and then continued with inventory count minimum, maximum, safety stock, the value of the average inventory, total inventory cost, turnover ratio and inventory turnover, followed by comparing results of a calculation method of the min-max with existing method, The results of applied research with min-max method was found to increased turnover ratio (TOR), inventory turnover (ITO), lower average inventory values and total inventory cost (TIC) to obtain reduce inventory cost.