Abstract: For a closed-loop supply chain system composed of a manufacturer and a retailer with new products and remanufactured products different pricing, corporate social responsibility (CSR) is taken into research. Closed-loop supply chain models respectively under centralized decision, decentralized decision making by the manufacturer alone and the retailer alone to exhibit CSR are constructed. The study discusses the impact of CSR and the optimal CSR exhibiting mode of the closed-loop supply chain. Besides, the study establishes a combined contract model with quantity discount and CSR performance cost sharing to achieve coordination. It is found that when the manufacturer or the retailer exhibits CSR alone, there is no clear evidence to distinguish which is better. For both of them, there is a great gap between the optimal decision of exhibiting CSR alone and the result of centralized decision. With the increasing of the replacement coefficient of new products and remanufactured ones, the competition between them becomes intensified, and the profits of each member and the whole supply chain also increase. If the manufacturer and the retailer can jointly exhibit CSR according to the combined contract of quantity discount and CSR performance cost sharing, the closed-loop supply chain system can achieve a coordinated effect and gain greater social welfare.

Key words: corporate social responsibility, two-period closed-loop supply chain, contract coordination