Abstract: In terms of order timing of short life cycle products, a retailer usually prefers to delayed order.But a manufacturer generally encourages the retailer to order in advance.So there is a conflict in the order timing issue between the manufacturer and the retailer.Coordinating the two sides can improve supply chain's overall performance.The existing papers about order timing of supply chain usually follow the risk-neutral hypothesis. And there are very few papers that conduct research in the case where the member of supply chain is risk-averse. Based on the newsboy model, in a two-echelon supply chain which is comprised of a risk-averse manufacturer and a risk-neutral retailer, the influence of the manufacturer's risk aversion on the order timing of the supply chain is discussed. It is found that in most case the supply chain may run in a mode which is not preferred by the manufacturer. Then a Buyback contract is designed to provide Pareto improvements. And the situation under which the Buyback contract can work is analyzed. Numerical analysis shows that, the setting of the wholesale price and the buyback price should consider both sides of the interests between the retailer and the manufacturer. In this way, the conditions of Pareto improvement could be meet. In addition, the smaller manufacturer's target profit is, the more easily Buyback contract could provide Pareto improvement. When the target profit gets larger to a certain degree, Buyback contract is no longer valid.The research gets some innovative achievements as follows: under the mode of flexible order, comparing with the risk-neutral situation, the optimal manufacturer's production is not independent of retailer's pre-ordering quantity, but is creasing in it; the retailer's pre-ordering quantity is larger than that of the general case owing to manufacturer's risk aversion. The research results have certain value to enrich literature of supply chain order timing.

Key words: risk aversion, order timing, supply chain coordination