Abstract: Being taken the impact of the information asymmetry on cost control in supply chain, a supply chain composed by a manufacturer and a retail was established. Supposing that the demand was time-related, in the two situations of information symmetry and information asymmetry, the whole profit situation of the manufacturer, the retail merchant and the supply chain was analyzed and the quantity discount coordinated mechanism was established accordingly. Research results showed that this reasonable coordination mechanism could effectively reduce the supply chain inventory cost. In the end, an example was made which illustrates the correlative conclusions.