Abstract:Considering the dynamic characteristics of product greenness and brand goodwill, price addition coefficient is introduced to describe the relationship among the purchase price, the wholesale price and the sales price, and the differential game is used to study the investment strategy and coordination of a three-level green supply chain composed of suppliers, manufacturers and retailers. The equilibrium results of the centralized decision model, the decentralized decision model without cost sharing contract and the decentralized decision model with cost sharing contract are compared and analyzed, and bilateral cost sharing contract is designed to coordinate the supply chain. The results show that: The optimal trajectory of product greenness has two variation trends, which are determined by the relationship between the initial value and the steady value of product greenness; The optimal trajectory of brand goodwill has three trends, which are determined by the relationship between the initial value and the steady value of brand goodwill; The centralized decision model is the best, and the decentralized decision model with cost sharing contract has limited Pareto improvement on the green supply chain, while the bilateral cost sharing contract can fully coordinate the green supply chain under certain conditions. In addition, the conditions and compatibility of the bilateral cost sharing contract are related to the price addition coefficients.