In this paper ,we explore the coordination of green supply chain under the background of the manufacturer's carbon emission reduction, green manufacturing R&D investment and the retailer' green marketing efforts.we also discuss the influence of cost sharing contract on key decisions of supply chain participants. On the basis of a green supply chain with environmental responsibility composed of a single manufacturer and a single retailer. Cost sharing contract for carbon emission reduction is established, which takes into account the carbon emission reduction of the manufacturer, green manufacturing R&D efforts and the retailer' marketing efforts. By comparing and analyzing the equilibrium levels of sub-problems such as product greening and profit under centralized decision, decentralized decision and cost-sharing contract decision. It is concluded that cost-sharing contract is beneficial to the improvement of green R&D level of the manufacturer and the increase of profits of supply chain participants. And the effectiveness of the cost sharing contract is positively related to the carbon reduction and sensitivity of consumers. Finally, the above conclusions are verified by numerical examples and relevant management suggestions are given.