In the context of both big data and low-carbon, the joint emission reduction and coordination issues in a three-echelon supply chain comprised of a manufacturer, a retailer and a big data service provider is studied. Considering that emission reduction has a dual impact on demand, this paper constructs the differential game models of the centralized, decentralized and improved bilateral cost-sharing contract. Then the optimal equilibrium strategies of supply chain members in three cases are solved and compared. Combined with a numerical example, the sensitivity analysis of some parameters are conducted, and the coordination effect of the contract on the supply chain is discussed, which provide a theoretical basis for the joint emission reduction and dynamic coordination in the supply chain involving big data service providers.