This research focuses on the case enterprise, a multinational specialty chemical company. The purpose is to solve its inventory control problem in supply chain. In this study, an efficient tool was developed to enhance supply chain management in order to decide inventory level appropriataely and predict the performance of supply chain operation. The research approach employed the discrete simulation the supply chain of case enterprise. The purpose is to design a supply chain simulation system in order to investgate its dynamic demand and stock status in practice. The system output includes performance measures such as strike rate, order cycle time, inventory performance , inventory holding expenses, production cost, selling cost, sales revenue and resource utilization . This study considers a four-echelon inventory system with uncertain demand and supply. There are four suppliers of raw material /packaging, one manufacturer, one distribution center, two retailers and its customers in system. Each member follows a periodic review (R, s, S) policy. The scenarios are designed by varying Re-order point (ROP) and Order-up-to level (OUL), the goal is to determine inventory policy for obtaining better performance in supply chain, such as lower inventory level, higher gross profit and higher service level at customer side. The contributions of this research is to choose the better simulation parameter to optimize the supply chain performance indicator by means of determining the appropriate inventory control policy. From the management point of view, the findings indicated that international interprise should store right amount of stock in reginal retailer. Increase stock overly had limited benefit to delivery performance, but high inventory level caused considerable negative impact on the performance of entire supply chain.