When a retailer is implementing an order postponement strategy in a supply chain system which is comprised of a supplier and two retailers, the impacts on the retailer, the supplier, the supply chain system are modeled and analyzed based on newsvendor model. Their preferences of order timing are obtained respectively. According to the service level, the figure of area distribution is depicted for the supplier and retailer’s order preference. Thus the Pareto optimal area is obtained when the retailer places an order. Our findings indicate that the supplier prefers the retailer’s advance order under mild conditions, but retailer usually prefers to delay his order, which are identical to the reality. Results also show that in some cases, it is favorable for the retailer to postpone his order from the supplier, but unfavorable to the system. When the supplier’s service level is high, it is beneficial to the retailer and the system as the retailer delays his order.