The traditional inventory management dominantly pays attention to the internal inventory control of busi2 ness , and is neglectful on supply chain coordination and partnering. The local optimization management mode results in impeded logistics , cost increase , lack of business and supply chain competitiveness. Supply chain coordination and partnering become significant means to improvement of supply chain performance , enhancement of business competitiveness. This paper makes some beneficial approaches to the inventory coordination and its value of the twostage supply chain under indeterminate supply and demand through model research. Under period review replenish2 ment , the paper introduces concept of effective inventory level , which represents upstream shortage’s influence on downstream inventory , models the inventory of suppler and buyer , and globally optimizes safety factor to reduce sup2 ply chain inventory cost . Meanwhile , authors present the realization mechanism of safety factor’s global optimiza2 tion , and make sensitivity analyses on value of global optimization.