中文摘要：

EPR制度是以现代环境管理原则实现产品系统环境性能改善的一种制度，它要求生产者不仅要对生产过程中的污染负责，而且还要对从产品设计到消费后废弃的全过程负责。本文引入了产品回收对销量的贡献率和设计改进对回收利润的贡献率概念．通过制造商激励与零售商努力投入，建立了闭环供应链委托代理契约模型。基于该模型．制造商可以设计最优激励契约，实现自身期望利润效用的最大化；零售商通过一定的销售努力和回收努力投入（最优努力投入）．可获得制造商提供的最优激励支付。从而。通过最优契约，实现闭环供应链的有效协调。

英文摘要：

EPR system is to improve the environmental performance of the product system through the modem environmental management principle. It requires that the producer shall be responsible not only for the pollution in the producing process but also for that in the whole process from the product design to its waste disposal. This paper introduces contribution rate of product recycling to sales volume and contribution rate of design improvement to recycling profit, and establishes closed loop supply chains （CLSC） principal- agent contract model. By analyzing the model, the paper concludes： the manufacturer can work out an optimal incentive contract to maximize its expected profit utility, and the dealer can acquire the optimal incentive payment provided by the manufacturer through their selling and recycling effort （the optimal effort input）, and finally achieve the CLSC cooperation through the optimal contract.