Due to increasing globalization, supply chain management has become a popular area of research. The issue of competition in the market place has evolved from between enterprises to between the supply chain networks. The global optimization of supply chain should be the main consideration. Supply chain competitiveness consists of high quality product, plus quick response time and flexibility. Efficient supply chain management enables enterprises to deliver their products at the right quantity, right place, right time and right quality. There is one phenomenon in the supply chain called “Bullwhip Effect” which happens when small changes of the demands downstream causes large fluctuation upstream. The closer to the upstream, the bigger the fluctuation. The objective of this study is to apply ( Manufacturer Managed Sale；MMS ) inventory cost model to improve supply chains information sharing, reduce the bullwhip effect, and minimize inventory cost. A simulation computer program is then developed. Numerical examples and sensitivity analysis are carried out to analyse and make comparison when MMS and (Vendor Managed Inventory；VMI) system are used.