Abstract: How to deal with the fluctuation of demand is an unavoidable problem for enterprises. The excess inventory or product out-of-stock caused by uncertain demand usually brings great risks to the normal operation of the enterprise. To this end, many strategies are proposed by industry and academia to reduce demand risk, which can be summarized into two main categories:on the one hand, the procurement flexibility should be increased as much as possible. Currently, quantity discount contract, quantity elasticity contract, repurchase contract are widely used; on the other hand, random demand should be transformed into definited demand as far as possible. At present, pre-sale strategy is widely used.
Generally, consumers can enjoy certain discount through pre-order. However, consumers may have a far cry from their psychological expectations after obtaining the products, so there are certain risks in pre-sale transaction. At present, many enterprises are skilled in applying option for purchasing,but option ideas are applied by few companies in pre-sale strategy. In fact, consumers are uncertainty about the valuation of commodities in the pre-sale phase. the actual utility value of consumers may be negative after getting the products. Therefore, when the option pre-sale strategies are offered by retailer, if the products can not reach the expected level of consumers, the pre-purchased consumers can give up exercising option to reduce risks. A kind of perishable product whose transport time affects the loss rate is considered in this paper. In the case of uncertain consumer valuation, the joint ordering and pre-selling strategy of retailer from the perspective of integration are studied. Retailer can purchase perishable items through wholesale price ordering or combined ordering, and consumers can choice discount pre-sale or option pre-sale which provided by retailer. Several different joint strategies are analyzed in detail through model construction. The optimal order quantity and pre-selling price under different strategies and the application range of different strategies are solved. Finally, the different combination strategies are compared.
The results show that the optimal total ordering quantity of retailer with combined ordering mode is higher than that with wholesale price ordering mode. The maximum expected profit of retailer under combined ordering mode is larger than that under wholesale price ordering mode. The retailer's order quantity within discount pre-sale strategy is larger than that within option pre-sale strategy; the exercise price in option pre-sale strategy is larger than that in discount pre-sale strategy. It is found that the risk of inventory backlog and product shortage caused by demand fluctuation can be reduced effectively through flexible purchase combined with option pre-sale, and the application range of option pre-sale strategy is broader than that of discount pre-sale strategy. The higher the economic value of products, the better it is for retailer and consumers to apply option pre-sale strategy. The results obtained from this paper can provide guidance for relevant studies and firms in practice.

Key words: perishable products, option, presale, order, discount, loss in transit