In this paper, the concept and primary design principles of ecological supply chain (ESC) are discussed. And the paper shows that companies can gain economical, social and environmental efficiencies simultaneously from implementing ecological supply chain management (ESCM). The cooperation processing based on by-product exchange in ESC is discussed with the decision-making criterion of eco-efficiency maximization. Accordingly, a pricing model is given. A case study of Guangxi Guitang Group is analyzed at last, which shows the multi-win brought by ESCM.