Maintaining inventory level is an important aspects in controlling the inventory cost. PT RST is a running single agent that hold Peugeot in Indonesia. PT RST is handling the sale of cars and handling the after sales service and spare parts. The company system of ordering the spare parts are done by historical data calculation that lead the company having an overstock problem and high inventory cost. Other researcher already given proposed order system by using the combination of ABC-XYZ classification and periodic review R,s,S and R,S. This final project is to provide an analysis by using system dynamic simulation whether the proposed system is affective or not. The process in making the dynamic simulation are identify the variable that related with the objective of the final project. Second is making the causal loop diagram to understand the relation in each variable. Last is making the stock and flow diagram to understand more comprehensive the model by quantitative data. A simulation-based system is made to analyze the systems that has been made.
Keyword: Overstock, Inventory Cost, System Dynamic, Causal Loop Diagram, Stock and Flow Diagram.