This paper analyzed the research status of supply chain knowledge sharing, and pointed out that the deficiency of knowledge sharing research in green supply chain. On the basis of existing researches, this paper compared and analyzed the characteristics of the knowledge sharing between the enterprises in green supply chain. For these characteristics, the corresponding principal-agent model was established based on principal-agent theory; and with the analysis and design of the model, this paper explored that the influence of various parameters change on the contract formation conditions. Finally, about the green supply chain how to implement the knowledge sharing effectively, this paper put forward the corresponding strategies, and built the knowledge sharing mechanism. It has a positive and far-reaching practical significance for achieving the optimal allocation of resources to reduce business costs and accelerating technological innovation and knowledge innovation of green supply chain.