中文摘要：

在由单一供应商和单一零售商组成的二级供应链系统中，考虑随机市场需求受零售商的销售努力水平的影响，建立了基本的回购契约模型。首先通过分析得出此基本模型未能实现供应链协调，因此，文章采取零售商和供应商共同承担努力成本的方法，建立了新的回购契约模型，并对供应链协调进行了分析，得出了零售商的最优订货量和最优努力水平。然后在考虑努力水平的同时，加入了零售商的风险偏好，建立了新的回购契约模型，并对供应链协调进行了重新分析。最后，通过算例分析验证了文章研究的相关结论。

英文摘要：

In the two echelon supply chain system consisting of a single supplier and a single retailer, market demand that is influenced by the level of retailer＇s sales effort is random,then this paper has established the basic buy-back eontraet model. First of all,through analyzing the basic model, it finds that this basic model can not achieve supply chain coordination. Therefore, this paper takes the method that effort costs are shared, thus it established the new buy-back contract model, and the supply chain coordination is analyzed. Also it is got the retailer＇s optimal order quantity and the optimal effort level. Then, it introduces the risk preference of retailers at the same time, and new buy-back contract model is established. It also gives the conditions for the supply chain to achieve coordination. Finally, the relevant conclusions of this study are verified by numerical examples.