中文摘要：

研究了非对称信息下一个制造商和一个零售商组成的两级闭环供应链在回购契约下的协调问题。在考虑零售商销售成本信息为非对称信息和随机性市场需求基础上，首先，分析了在正常状态下分散式系统决策情况，通过重新设计可变参数解决了信息不对称的问题，实现了回购契约下的信息共享和供应链的完美协调；然后，探讨了闭环供应链回购契约应对突发事件的协调问题。研究结果表明：当突发事件造成市场规模和制造商生产成本同时扰动时，闭环供应链的销售活动将受影响，闭环供应链的协调将被打破，而闭环供应链的废旧品回收活动却不受突发事件的影响。为此，给出了闭环供应链回购契约的应急决策。最后通过数值算例验证了结论。

英文摘要：

In recent years, emergency events such as nature disaster, terror attack etc. occur frequently, they affect the normal operation of enterprises and supply chain tremendously. Thus, this question leads to a wide attention about how to coordinate the supply chain to response to disruptions. In reality, because of the knowledge monopolization, industry barrier or benefit conflict, the asymmetric information between the retailer and the manufacturer is existed throughout, and the asymmetry of information is one of the causes which leading to the supply chain＇s low efficiency. The study motivation and origination of the paper is that the strategies on how to response the disruption under asymmetric information are explored so as to enhance the efficiency of the supply chain by studying the disruption management of the supply chain under asymmetric information. In this paper, a two-stageclosed-loop supply chain composed of one manu- facturer and one retailer is considered, while the disruptions cause the stochastic market demand distribution function and the manufacturer＇s production cost fluctuated simultaneously, how we should use the buy back contract to coordinate the supply chain under asymmetric information to response to the disruption. The paper＇s study method is to setup aclosed-loop supply chain coordination model under asymmetric information based on buy back contract firstly. As the disruption may affect the supply chain production plan and furthermore it would cause the manufacturer to adjust the production quantity, yet, the produc- tion quantity adjustment need to throw in deviation cost, so in the emergency environment, we setup a supply chain model based on a buy back contract by drawing （leading） into deviation cost. In addition, we analyze the model thoroughly. Basing on the retailer＇s facing asymmetric information of its selling costs and stochastic market demand, firstly the decentralized system decision situation under basic state, and solve the problem of asymmetric information is sol